Organic electroluminescence device

ABSTRACT

An organic electroluminescence device  1  includes: an anode  3,  a cathode  4  opposed to the anode  3  and an emitting layer  5  provided between the anode  3  and the cathode  4.  The emitting layer  5  contains first and second host materials and a luminescent material. The first host material has a partial structure represented by at least one of the following formulae (1) and (2) while the second host material has a partial structure represented by the following formula (3). Az represents a substituted or unsubstituted aromatic heterocyclic group containing a nitrogen-containing six-membered ring. W CN  is an aromatic hydrocarbon group substituted by at least one cyano group (CN) or an aromatic heterocyclic group substituted by at least one cyano group (CN). Ar 1  is a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted aromatic heterocyclic group, but is not an aromatic heterocyclic group containing a nitrogen-containing six-membered ring.
 
—Az—(W CN ) p    (1)
 
—Az—(CN) q    (2)
 
—Ar 1 —(CN) r    (3)

This application is a reissue application of U.S. Pat. No. 9,203,043issued Dec. 1, 2015 from U.S. application Ser. No. 13/902,355, andclaims priority to Japanese Patent Application No. 2012-121401, filedMay 28, 2012, and U.S. Provisional Application No. 61/657,313, filedJun. 8, 2012. The entire disclosure of Japanese Patent Application No.2012-121401, filed May 28, 2012, and U.S. Provisional Application No.61/657,313, filed Jun. 8, 2012, are expressly incorporated by referenceherein.

FIELD

Embodiments(s) described herein relate to an organic electroluminescencedevice.

BACKGROUND

When voltage is applied on an organic electroluminescence device(hereinafter, occasionally referred to as an organic EL device), holesand electrons are respectively injected into an emitting layer from ananode and a cathode. The injected electrons and holes are recombined inan emitting layer to form excitons. Here, according to the electron spinstatistics theory, singlet excitons and triplet excitons are generatedat a ratio of 25%:75%. In the classification according to the emissionprinciple, in a fluorescent EL device which uses emission caused bysinglet excitons, the limited value of an internal quantum efficiency ofthe organic EL device is believed to be 25%. On the other hand, in aphosphorescent EL device which uses emission caused by triplet excitons,it has been known that the internal quantum efficiency can be improvedup to 100% when intersystem crossing efficiently occurs from the singletexcitons.

In a typical organic EL device, the most suitable device design has beenmade depending on fluorescent emission mechanism or phosphorescentemission mechanism. Particularly for designing a phosphorescent organicEL device, it has been known that simple application of a fluorescentdevice technique to a phosphorescent organic EL device does not providea highly efficient phosphorescent organic EL device in consideration ofa luminescence property of the phosphorescent organic EL device. Thereasons are generally considered as follows.

First of all, since the phosphorescent emission is generated usingtriplet excitons, an energy gap of a compound for the emitting layermust be large. This is because a value of singlet energy (which means anenergy gap between energy in the lowest singlet state and energy in theground state) of a compound is typically larger than a value of tripletenergy (which means an energy gap between energy in the lowest tripletstate and energy in the ground state) of the compound.

Accordingly, in order to efficiently trap triplet energy of aphosphorescent dopant material in the device, first of all, a hostmaterial having larger triplet energy than that of the phosphorescentdopant material needs to be used in the emitting layer. Moreover, whenproviding an electron transporting layer and a hole transporting layeradjacently to the emitting layer, a compound having larger tripletenergy than that of the phosphorescent dopant material needs to be usedalso in the electron transporting layer and the hole transporting layer.Thus, according to the typical designing idea of the organic EL device,a compound having a larger energy gap than that of a compound used in afluorescent organic EL device is used in a phosphorescent organic ELdevice, thereby increasing drive voltage of the overall organic ELdevice.

Although a hydrocarbon compound exhibiting a high oxidation resistanceand a high reduction resistance is useful for the fluorescent device,the hydrocarbon compound has a broad δ-electron cloud to render theenergy gap small. For this reason, such a hydrocarbon compound isunlikely to be selected for the phosphorescent organic EL device, but anorganic compound including a hetero atom (e.g., oxygen and nitrogen) isselected. Consequently, a lifetime of the phosphorescent organic ELdevice is shorter than that of the fluorescent organic EL device.

Moreover, device performance of the phosphorescent organic EL device isgreatly affected by an exciton relaxation rate of triplet excitons muchlonger than that of singlet excitons in the phosphorescent dopantmaterial. In other words, with respect to emission from the singletexcitons, since a relaxation rate leading to emission is so fast thatthe singlet excitons are unlikely to diffuse to the neighboring layersof the emitting layer (e.g., the hole transporting layer and theelectron transporting layer), efficient emission is expected. On theother hand, with respect to emission from the triplet excitons, sincespin is forbidden and a relaxation rate is slow, the triplet excitonsare likely to diffuse to the neighboring layers, so that the tripletexcitons are thermally energy-deactivated unless the phosphorescentdopant material is a specific phosphorescent compound. In short, in thephosphorescent organic EL device, control of the recombination region ofthe electrons and the holes is more important as compared with thecontrol of that in the fluorescent organic EL device.

For the above reasons, enhancement of performance of the phosphorescentorganic EL device requires material selection and device designdifferent from those of the fluorescent organic EL device.

As a material of such a phosphorescent organic EL device, a carbazolederivative that exhibits a high triplet energy and is typically known asa hole transporting material has been used as a useful phosphorescenthost material.

Patent Literature 1 (International Publication No. WO2011/132683) andPatent Literature 2 (International Publication No. WO2011/132684) eachdisclose that a compound provided by introducing a nitrogen-containingheterocyclic group to a biscarbazole skeleton in which two carbazolesare bonded is used as a host material in an emitting layer of aphosphorescent organic EL device. The compounds disclosed in PatentLiteratures 1 and 2 are in a molecular design of well-balanced chargetransportation achieved by introducing an electron-deficientnitrogen-containing heterocyclic group to a hole-transporting carbazoleskeleton.

Moreover, Patent Literature 3 (International Publication No.WO2011/155507) discloses an organic EL device including an emittinglayer in which a plurality of host materials are mixed in an attempt toprolong a lifetime of the organic EL device. In Patent Literature 3,combinations of various host materials to be mixed are studied.

However, in the organic EL devices using the compounds disclosed inPatent Literatures 1 and 2, prolonging a lifetime of each of the organicEL devices is a technical problem.

Moreover, a lifetime of the organic EL device disclosed in PatentLiterature 3 is also desired to be prolonged.

BRIEF SUMMARY OF THE INVENTION

An object of the invention is to provide an organic electroluminescencedevice having a long lifetime.

After conducting concentrated studies in order to achieve the aboveobject, the inventors have found that a lifetime of an organic EL deviceis prolonged by using, as a first host material of an emitting layer, acompound having a partial structure of an aromatic heterocyclic ringincluding a nitrogen-containing six-membered ring to which a cyano groupis bonded directly or through a linking group and by using, as a secondhost material of the emitting layer, a compound having a partialstructure of an aromatic hydrocarbon ring bonded with a cyano group or apartial structure of an aromatic heterocyclic ring bonded with a cyanogroup, and reached the invention.

An organic electroluminescence device according to an aspect of theinvention includes: an anode; a cathode opposed to the anode; and anemitting layer provided between the anode and the cathode, in which theemitting layer includes a first host material, a second host materialand a luminescent material, the first host material includes a partialstructure represented by at least one of the following formulae (1) and(2), and the second host material includes a partial structurerepresented by the following formula (3) and does not comprise a partialstructure represented by the formula (1) or the formula (2).-Az-(W_(CN))_(p)   (1)-Az-(CN)_(q)   (2)-Ar¹-(CN)_(r)   (3)

In the formula (1), Az represents a substituted or unsubstitutedaromatic heterocyclic group comprising a nitrogen-containingsix-membered ring. W_(CN) is an aromatic hydrocarbon group substitutedby at least one cyano group (CN) or an aromatic heterocyclic groupsubstituted by at least one cyano group (CN). p is an integer of 1 ormore. W_(CN) optionally has a substituent other than the cyano groupand, when a plurality of W_(CN) are present, the plurality of W_(CN) aremutually the same or different.

In the formula (2), Az represents the same as Az of the formula (1), andq is an integer of 1 or more.

In the formula (3), Ar¹ is a substituted or unsubstituted aromatichydrocarbon group or a substituted or unsubstituted aromaticheterocyclic group, but is not an aromatic heterocyclic group comprisinga nitrogen-containing six-membered ring, and r is an integer of 1 ormore.

According to the above aspects of the invention, an organicelectroluminescence device having a long lifetime can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an exemplary arrangement of an organic ELdevice according to a first exemplary embodiment of the invention.

FIG. 2 schematically shows another exemplary arrangement of the organicEL device according to the first exemplary embodiment of the invention.

FIG. 3 schematically shows an exemplary arrangement of an organic ELdevice according to a second exemplary embodiment.

DETAILED DESCRIPTION OF THE INVENTION First Exemplary Embodiment

Organic EL Device

In a first exemplary embodiment of the invention, an organic EL deviceincludes: a cathode; an anode; and an organic thin-film layer providedbetween the cathode and the anode. The organic thin-film layer isconfigured to have a single layer or a plurality of layers.

In the organic EL device according to the exemplary embodiment, at leastone layer of the organic thin-film layer is an emitting layer.Accordingly, the organic thin-film layer may be provided by a singleemitting layer. Alternatively, the organic compound layer may beprovided by layers applied in a known organic EL device such as a holeinjecting layer, a hole transporting layer, an electron injecting layer,an electron transporting layer, a hole blocking layer, an electronblocking layer. The organic thin-film layer may include an inorganiccompound.

A compound according to the exemplary embodiment is contained in theorganic thin-film layer. When the organic thin-film layer is provided bya plurality of layers, the compound according to the exemplaryembodiment is contained singularly or as a component of a mixture in atleast one of the plurality of organic thin-film layers. Preferably, theemitting layer contains the compound according to the exemplaryembodiment. In this arrangement, it is preferable that the emittinglayer contains the compound according to the exemplary embodiment as ahost material and further contains a dopant material.

Typical device arrangements of an organic EL device include thefollowing arrangements (a) to (e) and the like:

(a) anode/emitting layer/cathode;

(b) anode/hole injecting⋅transporting layer/emitting layer/cathode;

(c) anode/emitting layer/electron injecting⋅transporting layer/cathode;

(d) anode/hole injecting⋅transporting layer/emitting layer/electroninjecting⋅transporting layer/cathode; and

(e) anode/hole injecting⋅transporting layer/emitting layer/blockinglayer/electron injecting⋅transporting layer/cathode.

While the arrangement (d) is preferably used among the abovearrangements, the arrangement of the invention is not limited to theabove arrangements.

It should be noted that the aforementioned “emitting layer” is anorganic layer having an emission function and, when a doping system isapplied, including a host material and a dopant material. Herein, thehost material has a function of mainly promoting recombination ofelectrons and holes and trapping excitons in the emitting layer whilethe dopant material has a function of making the excitons obtained inthe recombination efficiently emit. In a phosphorescent device, the hostmaterial has a function of trapping the excitons, which are generatedmainly in the dopant, within the emitting layer.

The “hole injecting/transporting layer” (or hole injecting⋅transportinglayer) means “at least one of a hole injecting layer and a holetransporting layer” while the “electron injecting/transporting layer”(or electron injecting-transporting layer) means “at least one of anelectron injecting layer and an electron transporting layer.” Herein,when the hole injecting layer and the hole transporting layer areprovided, the hole injecting layer is preferably adjacent to the anode.When the electron injecting layer and the electron transporting layerare provided, the electron injecting layer is preferably adjacent to thecathode.

In the exemplary embodiment, the electron transporting layer means anorganic layer having the highest electron mobility among organiclayer(s) providing an electron transporting zone existing between theemitting layer and the cathode. When the electron transporting zone isprovided by a single layer, the single layer is the electrontransporting layer. Moreover, in the phosphorescent organic EL device, ablocking layer having an electron mobility that is not always high maybe provided as shown in the arrangement (e) between the emitting layerand the electron transporting layer in order to prevent diffusion ofexciton energy generated in the emitting layer. Thus, the organic layeradjacent to the emitting layer does not always correspond to theelectron transporting layer.

The emitting layer may be of a double-dopant system in which at leasttwo kinds of dopant materials having a high quantum efficiency areintroduced and each of the dopants emits. Specifically, a host, a reddopant and a green dopant are co-evaporated on the emitting layer,whereby the emitting layer is commonly used to emit yellow light.

When the emitting layer is a laminate in which a plurality of emittinglayers are laminated, electrons and holes are accumulated at theinterface of the emitting layers, whereby a recombination regionconcentrates on the interface of the emitting layers to improve thequantum efficiency.

Injectability into the emitting layer of the holes may differ from thatof the electrons and transporting capabilities of the hole and theelectrons (represented by mobilities of the holes and the electrons inthe emitting layer) may differ from each other.

FIG. 1 schematically shows an exemplary arrangement of an organic ELdevice according to an exemplary embodiment of the invention.

An organic EL device 1 shown in FIG. 1 includes a substrate 2, an anode3, a cathode 4 and an organic thin-film layer 10 disposed between theanode 3 and the cathode 4.

The organic thin-film layer 10 includes a hole transporting layer 6, anemitting layer 5 and an electron transporting layer 7 which aresequentially laminated from the anode 3.

As another exemplary arrangement of the arrangement (d), as shown inFIG. 2, the organic thin-film layer 10 further includes a hole injectinglayer 8 and an electron injecting layer 9 to provide an organic ELdevice 1A.

Emitting Layer

The emitting layer 5 contains a first host material, a second hostmaterial and a phosphorescent dopant material as a luminescent material.

A content ratio of the first host material and the second host materialin the emitting layer is not particularly limited but adjustable asneeded. The ratio by mass is preferably in a range of 1:99 to 99:1 (thehost material: the second host material), more preferably of 10:90 to90:10.

The organic EL device according to the exemplary embodiment can exhibita prolonged lifetime by combining the first host material having atleast one of a partial structure represented by the following formula(1) and a partial structure represented by the following formula (2)with the second host material having a partial structure represented bythe following formula (3) to be used in the emitting layer. It isbelieved that mixture of the first and second host materials each havinga specific partial structure promotes probability of recombination ofholes and electrons to improve a luminous efficiency and a carrierbalance, thereby further prolonging the lifetime of the organic ELdevice.

First Host Material

The first host material used in the organic EL device according to theexemplary embodiment may be a compound having a partial structurerepresented by at least one of the following formulae (1) and (2).-Az-(W_(CN))_(p)   (1)-Az-(CN)_(q)   (2)

The first host material may include a plurality of partial structuresrepresented by the formula (1) or may include a plurality of partialstructures represented by the formula (2).

Alternatively, the first host material may be a single compoundincluding the partial structure represented by the formula (1) and thepartial structure represented by the formula (2).

Further alternatively, the first host material may a mixture including acompound having the partial structure represented by the formula (1) anda compound having the partial structure represented by the formula (2).

The first host material is preferably a compound having the partialstructure represented by the formula (1).

In the formulae (1) and (2), Az is a substituted or unsubstitutedaromatic heterocyclic group that contains a nitrogen-containingsix-membered ring. Examples of the aromatic heterocyclic grouprepresented by Az include: a monocyclic aromatic heterocyclic groupstructured by a monocyclic hetero ring (occasionally referred to as anon-fused aromatic heterocyclic group); and a fused aromaticheterocyclic group in which a hetero ring is fused to an aromatichydrocarbon ring or a hetero ring is fused to another hetero ring. Thearomatic heterocyclic group represented by Az preferably has 5 to 30ring atoms, more preferably 5 to 14 ring atoms.

Examples of the aromatic heterocyclic group represented by Az in theformulae (1) and (2) include a quinoline ring, isoquinoline ring,quinoxaline ring, phenanthridine ring, phenanthroline ring, pyridinering, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring,acridine ring, piperidine ring, morpholine ring, piperazine ring and agroup formed from derivatives thereof.

In the formula (1), W_(CN) is an aromatic hydrocarbon group substitutedby at least one cyano group (CN) or an aromatic heterocyclic groupsubstituted by at least one cyano group (CN).

In the formula (1), p represents an integer of 1 or more and is definedas the number of W_(CN) bondable to Az, the number depending on astructure of Az.

It should be noted that W_(CN) may have a substituent other than a cyanogroup. This substituent will be described later.

When a plurality of W_(CN) are present, the plurality of W_(CN) may bemutually the same or different.

In the formula (2), q represents an integer of 1 or more and is definedas the number of the cyano group (—CN) bondable to Az, the numberdepending on a structure of Az. p and q are preferably 1 or 2, morepreferably 1.

The aromatic hydrocarbon group for W_(CN) in the formula (1) preferablyhas 6 to 30 ring carbon atoms, more preferably 6 to 14 ring carbonatoms.

Examples of the aromatic hydrocarbon group for W_(CN) include a phenylgroup, naphthyl group, phenanthryl group, biphenyl group, terphenylgroup, quaterphenyl group, fluoranthenyl group, triphenylenyl group,phenanthrenyl group, fluorenyl group, spirofluorenyl group,9,9-diphenylfluorenyl group, 9,9′-spirobi[9H-fluorene]-2-yl group,9,9-dimethylfluorenyl group, benzo[c]phenanthrenyl group,benzo[a]triphenylenyl group, naphtho[1,2-c]phenanthrenyl group,naphtho[1,2-a]triphenylenyl group, dibenzo[a,c]triphenylenyl group andbenzo[b]fluoranthenyl group.

Preferable examples of the aromatic hydrocarbon group for W_(CN) includea phenyl group, naphthyl group, biphenyl group, terphenyl group,phenanthryl group, triphenylenyl group, fluorenyl group,spirobifluorenyl group and fluoranthenyl group.

The aromatic heterocyclic group for W_(CN) in the formula (1) preferablyhas 5 to 30 ring atoms, more preferably 5 to 14 ring carbon atoms.

Specific examples of the aromatic heterocyclic group for W_(CN) include,in addition to the same group as those of the specific examples of thearomatic heterocyclic group represented by Az, a pyrrole ring, isoindolering, benzofuran ring, isobenzofuran ring, dibenzothiophen ring, indolering, pyrrolidine ring, dioxane ring, carbazole ring, furan ring,thiophen ring, oxazole ring, oxadiazole ring, benzooxazole ring,thiazole ring, thiadiazole ring, benzothiazole ring, triazole ring,imidazole ring, benzoimidazole ring, pyrane ring, dibenzofuran ring,benzo[c]dibenzofuran ring and a group formed from derivatives thereof.

Examples of a cyano-substituted aromatic hydrocarbon group having 6 to30 ring carbon atoms and a cyano-substituted heterocyclic group having 5to 30 ring atoms include a cyano-substituted phenyl group, acyano-substituted biphenyl group, a cyano-substituted naphthyl group, acyano-substituted phenanthryl group, a cyano-substituted9,9-diphenylfluorenyl group, a cyano-substituted9,9′-spirobi[9H-fluorene]-2-yl group, a cyano-substituted9,9-dimethylfluorenyl group, a cyano-substituted dibenzothiophenylgroup, a cyano-substituted triphenyl group, and a cyano-substituteddibenzofuranyl group.

W_(CN) is more preferably a cyano-substituted phenyl group, acyano-substituted biphenyl group, a cyano-substituted9,9-diphenylfluorenyl group, a cyano-substituted9,9′-spirobi[9H-fluorene]-2-yl group, a cyano-substituted9,9-dimethylfluorenyl group, a cyano-substituted dibenzofuranyl group,and a cyano-substituted dibenzothiophenyl group.

W_(CN) is more preferably a cyano-substituted phenyl group, acyano-substituted biphenyl group such as 4-cyanobiphenyl group,3-cyanobiphenyl group and 2-cyanobiphenyl group, a cyano-substituted9,9-diphenylfluorenyl group, a cyano-substituted9,9′-spirobi[9H-fluorene]-2-yl group, a cyano-substituted9,9-dimethylfluorenyl group, a cyano-substituted dibenzofuranyl group,and a cyano-substituted dibenzothiophenyl group.

Since W_(CN) of the partial structure in the formula (1) is acyano-substituted phenyl group, a cyano-substituted biphenyl group or acyano-substituted fluorenyl, triplet energy level of W_(CN) tends to belarger than that of the cyano group of the partial structure in theformula (2). Accordingly, the compound having W_(CN) of the partialstructure in the formula (1) is further preferable since exhibiting anincreased luminous efficiency when contained in the emitting layer ofthe organic EL device.

Az in the formulae (1) and (2) is preferably a divalent to pentavalentgroup of a ring represented by the following formula (4-6).

The partial structures represented by the formulae (1) and (2) arepreferably structures represented by the following formulae (1-a) and(2-b).

In the formula (4-6), Y¹¹ to Y¹⁵ each independently represent a nitrogenatom (N) or CR^(c). CR^(c) is provided by R^(c) bonded to a carbon atom(C).

In CR^(c), R^(c) each independently represents a hydrogen atom, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted aromatic heterocyclicgroup having 5 to 30 ring atoms, a substituted or unsubstituted alkylgroup having 1 to 30 carbon atoms, a substituted or unsubstituted silylgroup, or a halogen atom.

When adjacent two of Y¹¹ to Y¹⁵ are CR^(c), a part of R^(c) of theadjacent CR^(c) may be bonded to a part of the other R^(c) to form acyclic structure.

When a plurality of R^(c) are present, the plurality of R^(c) aremutually the same or different.

Examples of the aromatic hydrocarbon group for R^(c) in CR^(c) are thesame as those of the aromatic hydrocarbon group for W_(CN).

Examples of the aromatic heterocyclic group for R^(c) in CR^(c) are thesame as those of the aromatic heterocyclic group for W_(CN).

The alkyl group for R^(c) in CR^(c) preferably has 1 to 6 carbon atoms.Examples of the alkyl group for R^(c) in CR^(c) include a methyl group,ethyl group, n-propyl group, isopropyl group, n-butyl group, s-butylgroup, isobutyl group, t-butyl group, n-pentyl group, n-hexyl group,n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecylgroup, n-dodecyl group, n-tridecyl group, n-tetradecyl group,n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecylgroup, neo-pentyl group, 1-methylpentyl group, cyclopropyl group,cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group,and adamantyl group.

Preferable examples of the alkyl group for R^(c) in CR^(c) include amethyl group, ethyl group, n-propyl group, isopropyl group, n-butylgroup, s-butyl group, isobutyl group, t-butyl group, cyclopentyl groupand cyclohexyl group. Further, the alkyl group also may be alternativelya haloalkyl group, examples of which include ones provided bysubstituting at least one hydrogen atom of the above alkyl group with ahalogen atom. The halogen atom is preferably fluorine. The haloalkylgroup is exemplified by a trifluoromethyl group and a 2,2-trifluoroethylgroup.

Examples of the silyl group for R^(c) in CR^(c) include a trimethylsilylgroup, triethylsilyl group, tributylsilyl group, dimethylethylsilylgroup, t-butyldimethylsilyl group, vinyldimethylsilyl group,propyldimethylsilyl group, dimethylisopropylsilyl group,dimethylpropylsilyl group, dimethylbutylsilyl group,dimethyl-tertiary-butylsilyl group, diethylisopropylsilyl group,phenyldimethylsilyl group, diphenylmethylsilyl group,diphenyl-tertiary-butylsilyl group and triphenylsilyl group.

Preferable examples of the silyl group for R^(c) in CR^(c) include atrimethylsilyl group, triethylsilyl group, t-butyldimethylsilyl group,vinyldimethylsilyl group and propyldimethylsilyl group.

Examples of the halogen atom for R^(c) in CR^(c) include fluorine,chlorine, bromine and iodine, among which fluorine is preferable.

As the monocyclic aromatic heterocyclic group for Az, a substituted orunsubstituted pyrimidine ring, a substituted or unsubstituted triazinering or a substituted or unsubstituted pyridine ring is preferable.

The partial structure represented by the formula (1) is exemplified inthe following list of groups. The partial structure represented by theformula (2) is exemplified by the following list of groups in whichW_(CN) is replaced by a cyano group (—CN).

In the above formulae representing the above partial structures, Rrepresents a substituent, which is the same as those for R^(c) in CR^(c)of the formula (4-6). R is preferably a substituted or unsubstitutedphenyl group, a substituted or unsubstituted biphenyl group, asubstituted or unsubstituted fluorenyl group, a substituted orunsubstituted naphthyl group, a substituted or unsubstituteddibenzofuranyl group, and a substituted or unsubstituted thiophenylgroup.

In the above formulae representing the above partial structures, W_(CN)represents the same as those for W_(CN) in the above. p is an integer of1 to 5.

The first host material is preferably represented by at least one of theformulae (1-1) and (2-1).A²-Az-(W_(CN))_(p)   (1-1)Ar²-Az-(CN)_(q)   (2-1)

In the formulae (1-1) and (2-1), Ar² represents a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, or substituted or unsubstituted aromatic heterocyclic grouphaving 5 to 30 ring atoms.

The same description of the aromatic hydrocarbon group for W_(CN) andthe same description of the aromatic heterocyclic group for W_(CN) applyto Ar².

Az, W_(CN) and p in the formula (1-1) are the same as Az, W_(CN) and pin the formula (1).

Az and q in the formula (2-1) are the same as Az and q in the formula(2).

The first host material is preferably represented by the followingformula (4).

In the formula (4), M¹ is a group represented by one of the formulae (1)and (2).

In the formula (4), L¹ represents a single bond, a substituted orunsubstituted polyvalent aromatic hydrocarbon group having 6 to 30 ringcarbon atoms, a substituted or unsubstituted polyvalent aromaticheterocyclic group having 5 to 30 ring atoms, or a group in which theabove groups are linked. “Polyvalent” means having valence of 2 or more.

In the formula (4), k is 1 or 2.

Examples of L¹ representing the polyvalent aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms are the same as those of the polyvalentaromatic hydrocarbon group described for W_(CN), among which a phenylenegroup, biphenylene group and naphthylene group are preferable.

Examples of L¹ representing the polyvalent aromatic heterocyclic grouphaving 6 to 30 ring carbon atoms are the same as those of the polyvalentaromatic heterocyclic group described for W_(CN), among which adibenzofuranylene group and dibenzothiophenylene group are preferable.

In the formula (4), X¹¹ to X¹⁸ each independently represent a nitrogenatom or CR^(b).

R^(b) each independently represents a hydrogen atom, a halogen atom, acyano group, a substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms, a substituted or unsubstitutedaromatic heterocyclic group having 5 to 30 ring atoms, a substituted orunsubstituted alkyl group having 1 to 30 carbon atoms, a substituted orunsubstituted alkenyl group having 2 to 30 carbon atoms, a substitutedor unsubstituted alkynyl group having 2 to 30 carbon atoms, asubstituted or unsubstituted alkylsilyl group having 3 to 30 carbonatoms, a substituted or unsubstituted arylsilyl group having 6 to 30ring carbon atoms, a substituted or unsubstituted alkoxy group having 1to 30 carbon atoms, a substituted or unsubstituted aralkyl group having6 to 30 ring carbon atoms, and a substituted or unsubstituted aryloxygroup having 6 to 30 ring carbon atoms.

A part of one of adjacent two R^(b) in X¹¹ to X¹⁸ is optionally bondedto a part of the other R^(b) to form a cyclic structure.

The same description of the aromatic hydrocarbon group for W_(CN)applies to the aromatic hydrocarbon group for R^(b).

The same description of the aromatic heterocyclic group for W_(CN)applies to the aromatic heterocyclic group for R^(b).

The same description of the alkyl group for R^(c) applies to the alkylgroup for R^(b).

The same description of the silyl group for R^(c) applies to thealkylsilyl group and arylsilyl group for R^(b).

The alkenyl group for R^(b) may be linear, branched or cyclic. Examplesof the alkenyl group are vinyl, propenyl, butenyl, oleyl,eicosapentaenyl, docosahexaenyl, styryl, 2,2-diphenylvinyl,1,2,2-triphenylvinyl and 2-phenyl-2-propenyl, among which a vinyl groupis preferable.

The alkynyl group for R^(b) may be linear, branched or cyclic. Examplesof the alkynyl group are ethynyl, propynyl and 2-phenylethynyl, amongwhich an ethynyl group is preferable.

The alkoxy group for R^(b) is represented by —OR^(W). R^(W) isexemplified by the alkyl group having 1 to 30 carbon atoms. Examples ofthe alkoxy group are a methoxy group, ethoxy group, propoxy group,butoxy group, pentyloxy group and hexyloxy group. The alkoxy group alsoincludes a haloalkoxy group, examples of which include ones provided bysubstituting at least one hydrogen atom of the above alkoxy group with ahalogen atom. The halogen atom is preferably fluorine.

The aralkyl group for R^(b) is represented by —R^(X)—R^(Y). R^(X) isexemplified by an alkylene group corresponding to the alkyl group having1 to 30 carbon atoms. R^(Y) is exemplified by the examples of thearomatic hydrocarbon group having 6 to 30 ring carbon atoms. In thearalkyl group, an aromatic hydrocarbon group moiety has 6 to 30 carbonatoms, preferably 6 to 20 carbon atoms, more preferably 6 to 12 carbonatoms. In the aralkyl group, an alkyl group moiety has 1 to 30 carbonatoms, preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbonatoms, further preferably 1 to 6 carbon atoms. Examples of the aralkylgroup are a benzyl group, 2-phenylpropane-2-yl group, 1-phenylethylgroup, 2-phenylethyl group, 1-phenylisopropyl group, 2-phenylisopropylgroup, phenyl-t-butyl group, α-naphthylmethyl group, 1-α-naphthylethylgroup, 2-α-naphthylethyl group, 1-α-naphthylisopropyl group,2-α-naphthylisopropyl group, β-naphthylmethyl group, 1-β-naphthylethylgroup, 2-β-naphthylethyl group, 1-β-naphthylisopropyl group,2-β-naphthylisopropyl group, 1-pyrorylmethyl group, 2-(1-pyroryl)ethylgroup, p-methylbenzyl group, m-methylbenzyl group, o-methylbenzyl group,p-chlorobenzyl group, m-chlorobenzyl group, o-chlorobenzyl group,p-bromobenzyl group, m-bromobenzyl group, o-bromobenzyl group,p-iodobenzyl group, m-iodobenzyl group, o-iodobenzyl group,p-hydroxybenzyl group, m-hydroxybenzyl group, o-hydroxybenzyl group,p-aminobenzyl group, m-aminobenzyl group, o-aminobenzyl group,p-nitrobenzyl group, m-nitrobenzyl group, o-nitrobenzyl group,p-cyanobenzyl group, m-cyanobenzyl group, o-cyanobenzyl group,1-hydroxy-2-phenylisopropyl group and 1-chloro-2-phenylisopropyl group.

The aryloxy group having 6 to 30 ring carbon atoms for R^(b) isrepresented by —OR^(Z). R^(Z) is exemplified by the aromatic hydrocarbongroup having 6 to 30 ring carbon atoms or the following monocyclic groupand fused cyclic group. The aryloxy group is exemplified by a phenoxygroup.

The first host material is preferably represented by at least one of theformulae (4-3) and (4-4).

In the formulae (4-3) and (4-4), L¹ and X¹¹ to X¹⁸ are the same as L¹and X¹¹ to X¹⁸ in the formula (4).

Az, W_(CN) and p in the formula (4-3) are the same as Az, W_(CN) and pin the formula (1).

Az and q in the formula (4-4) are the same as Az and q in the formula(1).

In the formulae (4), (4-3) and (4-4), preferably, X¹¹ to X¹⁸ eachindependently represent CR^(b).

Moreover, the first host material is preferably represented by thefollowing formula (4-5).

In the formula (4-5), L¹ is the same as L¹ in the formula (4-5).

In the formula (4-5), X¹¹ to X¹⁴ and X⁴⁵ to X⁴⁸ each independentlyrepresent a nitrogen atom or CR^(b).

In the formula (4-5), X¹⁵ to X¹⁸ and X⁴¹ to X⁴⁴ each independentlyrepresent a nitrogen atom, CR^(b) or a carbon atom to be bonded to L².

R^(b) of CR^(b) in X¹¹ to X¹⁸ and X⁴¹ to X⁴⁸ is the same as R^(b) ofCR^(b) in X¹¹ to X¹⁸ in the formula (4).

In the formula (4-5), L² and L³ each independently represents a singlebond, A³ represents a substituted or unsubstituted divalent aromatichydrocarbon group having 6 to 30 ring carbon atoms, a substituted orunsubstituted divalent aromatic heterocyclic group having 5 to 30 ringatoms, a cycloalkylene group having 5 to 30 ring carbon atoms, or agroup in which the above groups are linked.

Examples of L² and L³ representing the divalent aromatic hydrocarbongroup having 6 to 30 ring carbon atoms are the same as those of thedivalent aromatic hydrocarbon group described for W_(CN), among which aphenylene group, biphenylene group and naphthylene group are preferable.

Examples of L² and L³ representing the divalent aromatic heterocyclicgroup having 5 to 30 ring atoms are the same as those of the divalentaromatic heterocyclic group described for W_(CN), among which adibenzofuranylene group and dibenzothiophenylene group are preferable.

L² is preferably a single bond, a substituted or unsubstituted divalentmonocyclic hydrocarbon group having 6 ring carbon atoms, or asubstituted or unsubstituted divalent monocyclic aromatic heterocyclicgroup having at most 6 ring atoms. Among the above, L² is preferably aphenylene group, a group provided by bonding two or three phenylenegroups, or single bond.

In the formula (4-5), R^(b) represents the same as those for R^(b) inthe formulae (4-1) and (4-2).

In the formula (4-5), a part of one of at least adjacent two R^(b) inX¹¹ to X¹⁸ and X⁴¹ to X⁴⁸ may be bonded to a part of the other R^(b) toform a cyclic structure.

In the formula (4), M¹ is a group represented by one of the formulae (1)and (2).

In the formula (4-5), M² represents a substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms, asubstituted or unsubstituted aromatic heterocyclic group having 5 to 30ring atoms, or a group represented by one of the formulae (1) and (2),and M¹ and M² are the same or different.

The same description of the aromatic hydrocarbon group for W_(CN)applies to the aromatic hydrocarbon group for M².

The same description of the aromatic heterocyclic group for W_(CN)applies to the aromatic heterocyclic group for M².

In the formula (4-5), preferably, X¹⁵ to X¹⁸ each independentlyrepresent CR^(b) unless being a carbon atom to be bonded to L² while X¹¹to X¹⁴ each independently represent CR^(b).

In the formula (4-5), preferably, X⁴¹ to X⁴⁴ each independentlyrepresent CR^(b) unless being a carbon atom to be bonded to L² while X⁴⁵to X⁴⁸ each independently represent CR^(b).

In the formula (4-5), preferably, X¹⁵ to X¹⁸ each independentlyrepresent CR^(b) unless being a carbon atom to be bonded to L², and X⁴¹to X⁴⁴ each independently represent CR^(b) unless being a carbon atom tobe bonded to L² while X¹¹ to X¹⁴ and X⁴⁵ to X⁴⁸ each independentlyrepresent CR^(b).

In the first host material, the partial structures represented by theformulae (1) and (2) (i.e., an electron-transporting unit) arepreferably introduced at ends of a biscarbazole skeleton. In thisarrangement, the first host material has a favorable carrier balance ina molecule without counteraction between characteristics of ahole-injecting⋅transporting carbazolyl skeleton and characteristics of agroup having an electron-injecting⋅transporting cyano group.

The first host material represented by the formula (4-5) is preferablyone of a compound represented by the following formula (4-5-1), acompound represented by the following formula (4-5-2), and a compoundrepresented by the following formula (4-5-3).

In the formulae (4-5-1), (4-5-2) and (4-5-3), M¹, M², L¹, L², L³, X¹¹ toX¹⁸, and X⁴¹ to X⁴⁸ represent the same as M¹, M², L¹, L², L³, X¹¹ toX¹⁸, and X⁴¹ to X⁴⁸ in the formula (4-5).

In the formula (4-5-1), preferably, X¹¹ to X¹⁵, X¹⁷, X¹⁸, X⁴¹, X⁴², andX⁴⁵ to X⁴⁸ each independently represent CR^(b).

In the formula (4-5-2), preferably, X¹¹ to X¹⁵, X¹⁷, X¹⁸, X⁴¹, and X⁴³to X⁴⁸ each independently represent CR^(b).

In the formula (4-5-3), preferably, X¹¹ to X¹⁶, X¹⁸, X⁴¹, and X⁴⁴ to X⁴⁸each independently represent CR^(b).

In the invention, “carbon atoms forming a ring (ring carbon atoms)” meancarbon atoms forming a saturated ring, unsaturated ring, or aromaticring. “Atoms forming a ring (ring atoms)” mean carbon atoms and heteroatoms forming a hetero ring including a saturated ring, unsaturatedring, or aromatic ring.

In the invention, a “hydrogen atom” means isotopes having differentneutron numbers and specifically encompasses protium, deuterium andtritium.

Examples of the substituent meant by “substituted or unsubstituted” arethe above-described aromatic hydrocarbon group, aromatic heterocyclicgroup, alkyl group (linear or branched alkyl group, cycloalkyl group andhaloalkyl group), alkoxy group, aryloxy group, aralkyl group, haloalkoxygroup, alkylsilyl group, dialkylarylsilyl group, alkyldiarylsilyl group,triarylsilyl group, halogen atom, cyano group, hydroxyl group, nitrogroup and carboxy group. In addition, the alkenyl group and alkynylgroup are also usable. Examples of the substituents other than CN forW_(CN) as described above are the substituents described herein.

In the above-described substituents, the aromatic hydrocarbon group,aromatic heterocyclic group, alkyl group, halogen atom, alkylsilylgroup, arylsilyl group and cyano group are preferable. Preferable onesof the specific examples of each substituent are further preferable.

“Unsubstituted” in “substituted or unsubstituted” means that a group isnot substituted by the above-described substituents but bonded with ahydrogen atom.

Herein, “a to b carbon atoms” in the description of “substituted orunsubstituted XX group having a to b carbon atoms” represent carbonatoms of an unsubstituted XX group and does not include carbon atoms ofa substituted XX group.

In a later-described compound or a partial structure thereof, the sameapplies to the description of “substituted or unsubstituted.”

A manufacturing method of the first host material is not particularlylimited, but known methods are usable. For instance, the first hostmaterial may be manufactured by a coupling reaction using a coppercatalyst described in “Tetrahedron, 40th volume (1984), p. 1435-1456” ora palladium catalyst described in “Journal of the American ChemicalSociety, 123 (2001), p. 7727-7729.”

Examples of specific structures of the compounds usable as the firsthost material are shown below. However, the invention is not limited tothe compounds having these structures. It should be noted that a bond atan end of the following structural formulae, of which chemical formula(e.g., CN or a benzene ring) is not described, represents a methylgroup.

Second Host Material

The second host material used in the organic EL device according to theexemplary embodiment may be a compound having a partial structurerepresented by the following formula (3) and having no partial structurerepresented by the formula (1) or (2).—Ar¹—(CN)_(r)   (3)

In the formula (3), Ar¹ is a substituted or unsubstituted aromatichydrocarbon group or a substituted or unsubstituted aromaticheterocyclic group. The same description of the aromatic hydrocarbongroup and the aromatic heterocyclic group for W_(CN) applies to thearomatic hydrocarbon group and the aromatic heterocyclic group for Ar¹.It should be noted that Ar¹ is not an aromatic heterocyclic groupincluding a nitrogen-containing six-membered ring.

In the formula (3), r represents the number of the cyano group (—CN)substituting for Ar¹ and is an integer of 1 or more. r is determined asthe number of the cyano group bondable to r depending on a structure ofAr¹.

In the formula (3), the cyano-substituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms and the cyano-substituted aromaticheterocyclic group having 5 to 30 ring atoms may be further substitutedby a substituent other than a cyano group. The substituent herein is thesame as those for the first host material.

The second host material may have a plurality of partial structuresrepresented by the formula (3). In this arrangement, the partialstructures represented by the formula (3) are mutually the same ordifferent.

In addition, a mixture of plural kinds of compounds may be used as thesecond host material.

The second host material is preferably represented by the followingformula (3-1).Ar³—Ar¹—(CN)_(r)   (3-1)

In the formula (3-1), Ar³ represents a substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms, orsubstituted or unsubstituted aromatic heterocyclic group having 5 to 30ring atoms. The same description of the aromatic hydrocarbon group forW_(CN) and the same description of the aromatic heterocyclic group forW_(CN) apply to Ar³.

Ar¹ and r in the formula (3-1) are the same as Ar¹ and r in the formula(3).

The second host material is preferably represented by the followingformula (5).

In the formula (5), A¹ is a group represented by the formula (3).

In the formula (5), X¹ to X⁸ each independently represent N (nitrogenatom) or CR^(a).

In the formula (5), R^(a) each independently represents a hydrogen atom,a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted aromatic heterocyclicgroup having 5 to 30 ring atoms, a substituted or unsubstituted alkylgroup having 1 to 30 carbon atoms, a substituted or unsubstituted silylgroup, a halogen atom, or a cyano group. When a plurality of R^(a) arepresent, the plurality of R^(a) are the same or different. R^(a)represents the same as those for R^(c) in the first host material.

In the formula (5), when adjacent two of X¹ to X⁸ are CR^(a), a part ofR^(a) in the adjacent CR^(a) may be bonded to a part of the other R^(a)to form a cyclic structure.

When a plurality of R^(a) are present, the plurality of R^(a) may bemutually the same or different.

In the formula (5), preferably, X¹ to X⁸ each independently representCR^(a).

The second host material is preferably represented by the followingformula (5-1).

In the formula (5-1), A¹ represents a group having a partial structurerepresented by the formula (3).

In the formula (5-1), A² each independently represents the group havingthe partial structure represented by the formula (3), a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, or a substituted or unsubstituted aromatic heterocyclic grouphaving 5 to 30 ring atoms.

The same description of the aromatic hydrocarbon group for W_(CN) in thefirst host material applies to the aromatic hydrocarbon group for A².

The same description of the aromatic heterocyclic group for W_(CN) inthe first host material applies to the aromatic heterocyclic group forA².

When A² is the group having the partial structure represented by theformula (3), A¹ and A² may be the same group or different groups.

In the formula (5-1), A³ represents A³ represents a substituted orunsubstituted divalent aromatic hydrocarbon group having 6 to 30 ringcarbon atoms, a substituted or unsubstituted divalent aromaticheterocyclic group having 5 to 30 ring atoms, a substituted orunsubstituted cycloalkylene group having 5 to 30 ring carbon atoms, or agroup in which the above groups are linked.

Examples of A³ representing the divalent aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms are the same as those of the divalentaromatic hydrocarbon group described for W_(CN), among which a phenylenegroup, biphenylene group and naphthylene group are preferable.

Examples of A³ representing the divalent aromatic heterocyclic grouphaving 6 to 30 ring carbon atoms are the same as those of the divalentaromatic heterocyclic group described for W_(CN), among which adibenzofuranylene group and a dibenzothiophenylene group are preferable.

In the formula (5-1), m is an integer of 0 to 3. m is preferably aninteger of 0 to 2, more preferably 0 or 1. When m is 0, one of X⁵ to X⁸is bonded to one of Y¹ to Y⁴ through a single bond.

Moreover, A³ is preferably a single bond, a substituted or unsubstituteddivalent monocyclic hydrocarbon group having at most 6 ring carbonatoms, or a substituted or unsubstituted divalent monocyclic aromaticheterocyclic group having at most 6 ring atoms.

Examples of A³ representing the monocyclic hydrocarbon group having atmost 6 ring carbon atoms include a phenylene group, cyclopentenylenegroup, cyclopentadienylene group, cyclohexylene group and cyclopentylenegroup, among which a phenylene group is preferable.

Examples of A³ representing the monocyclic heterocyclic group having atmost 6 ring atoms include a pyrrolylene group, pyrazinylene group,pyridinylene group, furylene group and thiophenylene group.

In the formula (5-1), it is preferable that m is 0 and one of X⁵ to X⁸is bonded to one of Y¹ to Y⁴ through a single bond, or alternatively, A³is a substituted or unsubstituted monocyclic hydrocarbon group having atmost 6 ring carbon atoms, or a substituted or unsubstituted monocyclicaromatic heterocyclic group having at most 6 ring atoms. In the above,it is preferable that m is 0 and one of X⁵ to X⁸ is bonded to one of Y¹to Y⁴ through a single bond, or alternatively, A³ is a substituted orunsubstituted phenylene group.

In the formula (5-1), X¹ to X⁴ and Y⁵ to Y⁸ each independently representN (nitrogen atom) or CR^(a).

In the formula (5-1), X⁵ to X⁸ and Y¹ to Y⁸ each independently representN (nitrogen atom), CR^(a) or a carbon atom to be bonded to A³.

R^(a) for CR^(a) in X¹ to X⁸ and Y¹ to Y⁸ each independently representsthe same as R^(a) in the formula (5). When a plurality of R^(a) arepresent, the plurality of R^(a) are the same or different.

When at least adjacent two of X¹ to X⁸ and Y¹ to Y⁸ are CR^(a), a partof R^(a) in the adjacent CR^(a) is optionally bonded to a part of theother R^(a) to form a cyclic structure.

One of X⁵ to X⁸ is a carbon atom and one of Y¹ to Y⁴ is a carbon atom.These carbon atoms are bonded to each other through A³.

In the formula (5-1), X¹ to X⁸ and Y¹ to Y⁸ each independently representCR^(a). It is preferable that one of X⁵ to X⁸ is a carbon atom and oneof Y¹ to Y⁴ is a carbon atom, in which these carbon atoms are bonded toeach other through A³.

In the formula (5-1), preferably, X⁵ to X⁸ each independently representCR^(a) unless being a carbon atom to be bonded A³, and Y¹ to Y⁴ eachindependently represent CR^(a) unless being a carbon atom to be bondedto A³ while X¹ to X⁴ and Y⁵ to Y⁸ each independently represent CR^(a).

The formula (5-1) may satisfy at least one of the following (ii) to (v).

(ii) At least one of X¹ to X⁴ and Y⁵ to Y⁸ is CR^(a) and at least one ofR^(a) in X¹ to X⁴ and Y⁵ to Y⁸ is a cyano-substituted aromatichydrocarbon group having 6 to 30 ring carbon atoms or acyano-substituted heterocyclic group having 5 to 30 ring atoms.

(iii) m is an integer of 1 to 3 and at least one of A³ is acyano-substituted divalent aromatic hydrocarbon group having 6 to 30ring carbon atoms or a cyano-substituted divalent heterocyclic grouphaving 5 to 30 ring atoms.

(iv) At least one of X⁵ to X⁸ and Y¹ to Y⁴ is CR^(a) and at least one ofR^(a) in X⁵ to X⁸ and Y¹ to Y⁸ is a cyano-substituted aromatichydrocarbon group having 6 to 30 ring carbon atoms or acyano-substituted heterocyclic group having 5 to 30 ring atoms.

(v) At least one of X¹ to X⁸ and Y¹ to Y⁸ is C—CN.

The second host material represented by the formula (5-1) having thepartial structure represented by the formula (3) has a structure inwhich an aromatic hydrocarbon group having a cyano group is introducedto an end of each of two rings (e.g., carbazole rings) which form acentral skeleton by being linked through A³.

The central skeleton serves as a hole-injecting⋅transporting unit. Thearomatic hydrocarbon group having a cyano group serves as anelectron-injecting⋅transporting unit. Since the aromatic hydrocarbongroup having a cyano group serving as an electron-injecting⋅transportingunit is introduced to the outer side of the central skeleton, the secondhost material keeps a spread of electron clouds of HOMO (highestoccupied molecular orbital) of the central skeleton to keep a favorablehole-injecting⋅transporting capability while exhibiting anelectron-injecting⋅transporting function provided by a group having acyano group. With this arrangement, carrier balance in a moleculebecomes favorable in the second host material. Accordingly, when thesecond host material is used in an organic EL device, the organic ELdevice can achieve an excellent luminous efficiency.

Consequently, in addition to the advantage to prolong the lifetime ofthe organic EL device according to the exemplary embodiment whichincludes the emitting layer including the second host material and thefirst host material, the luminous efficiency of the organic EL devicebecomes favorable.

The second host material represented by the formula (5-1) is preferablyrepresented by one of the following formulae (5-1-1), (5-1-2) and(5-1-3),

In the formula (5-1-1), A¹, A², A³, X¹ to X⁵, X⁷, X⁸, Y¹, Y², Y⁴ to Y⁸and m represent the same as A¹, A², A³, X¹ to X⁵, X⁷, X⁸, Y¹, Y², Y⁴ toY⁸ and m in the formula (5-1). X⁶ and Y³ are carbon atoms.

In the formula (5-1-1), preferably, X¹ to X⁵, X⁷, X⁸, Y¹, Y² and Y⁴ toY⁸ each independently represent CR^(a).

In the formula (5-1-2), A¹, A², A³, X¹ to X⁵, X⁷, X⁸, Y¹, Y³ to Y⁸ and mrepresent the same as A¹, A², A³, X¹ to X⁵, X⁷, X⁸, Y¹, Y³ to Y⁸ and min the formula (5-1). X⁶ and Y² are carbon atoms.

In the formula (5-1-2), preferably, X¹ to X⁵, X⁷, X⁸, Y¹ and Y³ to Y⁸each independently represent CR^(a).

In the formula (5-1-3), A¹, A², A³, X¹ to X⁶, X⁸, Y¹, Y², Y⁴ to Y⁸ and mrepresent the same as A¹, A², A³, X¹ to X⁶, X⁸, Y¹, Y², Y⁴ to Y⁸ and min the formula (5-1). X⁷ and Y³ are carbon atoms.

In the formula (5-1-3), preferably, X¹ to X⁶, X⁸, Y¹, Y² and Y⁴ to Y⁸each independently represent CR^(a).

At least one of the partial structures represented by the formula (3) ofthe second host material is preferably a cyano-substituted phenyl group,a cyano-substituted naphthyl group, a cyano-substituted phenanthrylgroup, a cyano-substituted dibenzofuranyl group, a cyano-substitutedbiphenylyl group, a cyano-substituted terphenylyl group, or acyano-substituted triphenylenyl group.

More preferably, A² of the second host material is not substituted by acyano group.

In the formula (5-1), A¹ and A² are preferably different from eachother. Specifically, the second host material preferably has anasymmetric structure. With such a structure, the second host materialexhibits favorable crystallinity and non-crystallinity. Accordingly,since the organic EL device using the second host material has anexcellent film quality, the organic EL device can achieve a highperformance in characteristics (e.g., current efficiency) of the organicEL.

A manufacturing method of the second host material is not particularlylimited, but known methods are usable. For instance, the second hostmaterial may be manufactured by a coupling reaction to a carbazolederivative and an aromatic halogenated compound using a copper catalystdescribed in “Tetrahedron, 40th volume (1984), p. 1435-1456” or apalladium catalyst described in “Journal of the American ChemicalSociety, 123 (2001), p. 7727-7729” to manufacture the biscarbazolederivative.

Specific examples of the second host material are described below, butthe compound of the exemplary embodiment is not limited thereto.

In the exemplary embodiment, the first host material is preferablyrepresented by at least one of the following formulae (1-2) and (2-2).Moreover, in the exemplary embodiment, the second host material ispreferably represented by the following formula (3-2).A-L¹⁰-Az

W_(CN))_(p)   (1-2)A-L¹⁰-Az

CN)_(q)   (2-2)A-L¹⁰-Ar¹

CN)_(r)   (3-2)

In the formulae (1-2), (2-2) and (3-2), Az, W_(CN), Ar¹, p, q and r arethe same as Az, W_(CN), Ar¹, p, q and r described above.

In the formulae (1-2), (2-2) and (3-2), L¹⁰ represents a divalentaromatic hydrocarbon group having 6 to 60 ring carbon atoms, or adivalent heterocyclic group having 5 to 60 ring atoms. L¹⁰ may have asubstituent. The divalent aromatic hydrocarbon group having 6 to 60 ringcarbon atoms for L¹⁰ is exemplified by an aromatic hydrocarbon grouphaving 6 to 60 ring carbon atoms represented by A described later ofwhich valence is changed to 2. The divalent aromatic heterocyclic grouphaving 5 to 60 ring carbon atoms for L¹⁰ is exemplified by an aromaticheterocyclic group having 5 to 60 ring carbon atoms represented by Adescribed later of which valence is changed to 2.

In the formulae (1-2), (2-2) and (3-2), A each independently representsan aromatic hydrocarbon group having 6 to 60 ring carbon atoms(preferably, having 6 to 30 ring carbon atoms), or a heterocyclic grouphaving 5 to 60 ring atoms (preferably, having 5 to 30 ring atoms). A mayhave a substituent. Examples of the aromatic hydrocarbon group having 6to 60 ring carbon atoms for A in the formulae (1-2), (2-2) and (3-2) arethe same as those of the aromatic hydrocarbon group for W_(CN) in theformula (1). Examples of the heterocyclic group having 5 to 60 ringatoms for A in the formulae (1-2), (2-2) and (3-2) are the same as thoseof the aromatic heterocyclic group for W_(CN) in the formula (1). A inthe formulae (1-2), (2-2) and (3-2) is preferably a group derived vrombenzene, naphthalene, phenanthrene, fluorene, triphenylene, dibenzofuranand carbazole and may have a substituent.

In the formulae (1-2), (2-2) and (3-2), A is preferably represented bythe following formula (10).

In the formula (10), R_(1a) to R_(8a) each independently represent ahydrogen atom or a substituent. At least one pair of adjacentsubstituents of R_(1a) to R_(8a) are bonded to each other to form acyclic structure represented yb the following formula (11).

In the formula (11), R_(10a) to R_(13a) each independently represent ahydrogen atom or a substituent.

X_(1a) in the formula (10) and Y_(1a) in the formula (11) eachindependently represent an oxygen atom, a sulfur atom, —NR₂₁— or—CR₂₂R₂₃—. R₂₁, R₂₂ and R₂₃ each independently represent a hydrogen atomor a substituent.

It should be noted that, in the formulae (10) and (11), one of R_(1a) toR_(8a), R_(10a) to R_(13a) and R₂₁ to R₂₃ is bonded to L¹⁰.

In the formulae (1-2), (2-2) and (3-2), A is preferably represented byone of the following formulae (12) to (17).

In the formulae (12) to (17), R₇₄ to R₁₃₉ each independently represent ahydrogen atom or a substituent.

In the formulae (12) to (17), Y₂₁, Y₃₁, Y₄₁, Y₅₁, Y₆₁ and Y₇₁ in theformulae (12) to (17) each independently represent an oxygen atom, asulfur atom, —NR₃₁— or —CR₃₂R₃₃—. R₃₁, R₃₂ and R₃₃ each independentlyrepresent a hydrogen atom or a substituent.

In the formula (12), one of R₇₄ to R₈₄ and R₃₁ to R₃₃ is bonded to L¹⁰.In the formula (13), one of R₈₅ to R₉₅ and R₃₁ to R₃₃ is bonded to L¹⁰.In the formula (14), one of R₉₆ to R₁₀₆ and R₃₁ to R₃₃ is bonded to L¹⁰.In the formula (15), one of R₁₀₇ to R₁₁₇ and R₃₁ to R₃₃ is bonded toL¹⁰. In the formula (16), one of R₁₁₈ to R₁₂₈ and R₃₁ to R₃₃ is bondedto L¹⁰. In the formula (17), one of R₁₂₉ to R₁₃₉ and R₃₁ to R₃₃ isbonded to L¹⁰.

In the formulae (1-2), (2-2) and (3-2), A is preferably represented bythe following formula (20).

In the formula (20), R₂₀, R₂₁ and R₂₂ each independently represent ahydrogen atom or a substituent. R₂₀, R₂₁ and R₂₂ is bonded to carbonatoms in a cyclic structure forming a triphenylene ring represented bythe formula (20). Adjacent substituents in R₂₀, R₂₁ and R₂₂ may form aring.

In the formula (20), r1 and r2 is 4, and r3 is 3.

In the formula (20), La is a divalent aromatic hydrocarbon group having6 to 60 ring carbon atoms or a divalent heterocyclic group having 5 to60 ring atoms. La may have a substituent. La is bonded to carbon atomsin a cyclic structure forming a triphenylene ring represented by theformula (20).

The substituents in the formulae (1-2), (2-2), (3-2), (12) to (17) and(20) represents the same as the aforementioned substituents.

Specific examples of the first host material in the exemplary embodimentare described below, but the compound of the exemplary embodiment is notlimited thereto.

Subsequently, specific examples of the second host material in theexemplary embodiment are described below, but the compound of theexemplary embodiment is not limited thereto.

Luminescent Material

Examples of a luminescent material contained in the emitting layer are afluorescent material and a phosphorescent material, among which thephosphorescent material is preferable.

The fluorescent material used as the dopant material (hereinafter,referred to as a fluorescent dopant material) is selected from afluoranthene derivative, pyrene derivative, arylacetylene derivative,fluorene derivative, boron complex, perylene derivative, oxadiazolederivative, anthracene derivative and chrysene derivative. Thefluoranthene derivative, pyrene derivative and boron complex arepreferable.

The dopant material of the organic EL device according to the exemplaryembodiment is preferably the phosphorescent material emittable in atriplet state. The phosphorescent material used as the dopant material(hereinafter, referred to as a phosphorescent dopant material)preferably contains a metal complex. The metal complex preferablycontains: a metal atom selected from iridium (Ir), platinum (Pt), osmium(Os), gold (Au), rhenium (Re) and ruthenium (Ru); and a ligand.Particularly, an ortho-metalated complex in which the ligand and themetal atom form an ortho-metal bond is preferable. As the phosphorescentdopant material, an ortho-metalated complex containing a metal selectedfrom the group consisting of iridium (Ir), osmium (Os) and platinum (Pt)is preferable since a phosphorescent quantum yield is high and anexternal quantum efficiency of an emitting device is improvable. Interms of the luminous efficiency, a metal complex including the ligandselected from phenyl quinoline, phenyl isoquinoline, phenyl pyridine,phenyl pyrimidine, phenyl pyrazine and phenyl imidazole is preferable.

A content of the dopant material in the emitting layer is notparticularly limited. Although the content thereof can be selectedaccording to the need, for instance, the content thereof is preferablyin a range of 0.1 mass % to 70 mass %, more preferably of 1 mass % to 30mass %. When the content of the dopant material is 0.1 mass % or more, asufficient emission is obtained. When the content of the dopant materialis 70 mass % or less, concentration quenching is avoidable.

It should be noted that a host material combined with a fluorescentdopant material is herein referred to as a fluorescent host materialwhile a host material combined with a phosphorescent dopant material isherein referred to as a phosphorescent host material. The fluorescenthost material and the phosphorescent host material are notdifferentiated only from molecular structures thereof. In other words,the phosphorescent host material herein means a material for forming aphosphorescent-emitting layer containing a phosphorescent dopantmaterial, and does not mean to be inapplicable to a material for forminga fluorescent-emitting layer. The same applies to a fluorescent hostmaterial.

Examples of the phosphorescent dopant material are shown below.

One kind of the phosphorescent dopant material may be singularly used,or two or more kinds thereof may be used in combination.

An emission wavelength of the phosphorescent dopant material containedin the emitting layer is not particularly limited, but at least one ofthe phosphorescent dopant material contained in the emitting layerpreferably has a peak of the emission wavelength in a range of 490 nm to700 nm, more preferably in a range of 490 nm to 650 nm. Preferableemission colors of the emitting layer are, for instance, red, yellow andgreen. Using the first and second host materials and doping thephosphorescent dopant material having such an emission wavelength toform the emitting layer, the organic EL device can exhibit a highefficiency and a long lifetime.

The phosphorescent host material is a compound having a function toenable the phosphorescent dopant material to emit efficiently byefficiently trapping triplet energy of the phosphorescent dopantmaterial in the emitting layer. The organic EL device according to theexemplary embodiment may select a compound other than the compounds ofthe first and second host materials as the phosphorescent host materialaccording to the object of the invention.

The first and second host materials and the other compound may be usedtogether in the same emitting layer. When a plurality of emitting layersare present, the first and second host materials may be used as aphosphorescent host material in one of the emitting layers while thecompound other than the first and second host materials may be used as aphosphorescent host material in another one of the emitting layers. Thefirst and second host materials may be used in the organic layer otherthan the emitting layer(s).

Specific examples of a preferable compound for the phosphorescent hostmaterial except for the compound for the first and second host materialsinclude a carbazole derivative, triazoles derivative, oxazolederivative, oxadiazole derivative, imidazoles derivative, polyarylalkanederivative, pyrazoline derivative, pyrazolone derivative,phenylenediamine derivative, arylamine derivative, amino-substitutedchalcone derivative, styryl anthracene derivative, fluorenonederivative, hydrazone derivative, stilbene derivative, silazanederivative, aromatic tertiary amine compound, styrylamine compound,aromatic dimethylidene compound, porphyrin compound,anthraquinodimethane derivative, anthrone derivative, diphenylquinonederivative, thiopyrandioxide derivative, carbodiimide derivative,fluorenylidenemethan derivative, distyryl pyrazine derivative,hyterocyclic tetracarboxylic acid anhydride such as naphthaleneperylene,phthalocyanine derivative, various metal complex polysilane compoundstypified by a metal complex of 8-quinolinol derivative, and a metalcomplex having metal phthalocyanine, benzoxazole or benzothiazole as theligand, poly(N-vinylcarbazole) derivative, aniline copolymer, conductivehigh molecular weight oligomers such as thiophene oligomer andpolythiophene, polymer compounds such as polythiophene derivative,polyphenylene derivative, polyphenylene vinylene derivative andpolyfluorene derivative. One kind of the phosphorescent host materialother than the first and second host materials may be singularly used,or two or more kinds thereof may be used in combination. Specifically,the following compounds are shown.

Hole Injecting⋅Transporting Layer

The hole injecting⋅transporting layer helps injection of holes to theemitting layer and transports the holes to an emitting region. The holeinjecting⋅transporting layer exhibits a large hole mobility and a smallionization energy.

The hole injecting transporting layer may be provided by a holeinjecting layer or a hole transporting layer, or alternatively, may beprovided by a laminate of a hole injecting layer and a hole transportinglayer.

A material for forming the hole injecting layer and the holetransporting layer is preferably a material for transporting the holesto the emitting layer at a lower electric field intensity. For instance,an aromatic amine compound is preferably used. A material for the holeinjecting layer is preferably a porphyrin compound, an aromatic tertiaryamine compound or a styryl amine compound, particularly preferably thearomatic tertiary amine compound such as hexacyanohexaazatriphenylene(HAT).

A material for forming the hole injecting⋅transporting layer ispreferably a material for transporting the holes to the emitting layerat a lower electric field intensity. For instance, an aromatic aminecompound represented by the following formula (A1) is preferably used.

In the formula (A1), Ar¹ to Ar⁴ each independently represent an aromatichydrocarbon group having 6 to 50 ring carbon atoms, an aromaticheterocyclic group having 2 to 40 ring carbon atoms, a group provided bybonding the aromatic hydrocarbon group and the aromatic heterocyclicgroup, or a group provided by bonding the aromatic hydrocarbon group andthe aromatic heterocyclic group.

Note that the aromatic hydrocarbon group and the aromatic heterocyclicgroup described herein may have a substituent.

In the formula (A1), L is a linking group and represents a divalentaromatic hydrocarbon group having 6 to 50 ring carbon atoms, a divalentaromatic heterocyclic group having 5 to 50 ring carbon atoms, and adivalent group provided by bonding at least two of the aromaticheterocyclic groups or the aromatic heterocyclic group through a singlebond, an ether bond, a thioether bond, an alkylene group having 1 to 20carbon atoms, an alkenylene group having 2 to 20 carbon atoms, or anamino group.

It should be noted that the divalent aromatic hydrocarbon group and thedivalent aromatic heterocyclic group described herein may have asubstituent.

Examples of the compound represented by the formula (A1) are shownbelow. However, the compound represented by the formula (A1) is notlimited thereto.

Aromatic amine represented by the following formula (A2) can also bepreferably used for forming the hole injecting/transporting layer.

In the above formula (A2), Ar¹ to Ar^(a) each represent the same as Ar¹to Ar⁴ of the above formula (A1). Examples of the compound representedby the formula (A2) are shown below. However, the compound representedby the formula (A2) is not limited thereto.

The hole transporting layer of the organic EL device according to theexemplary embodiment may have a double-layer structure of a first holetransporting layer (near the anode) and a second hole transporting layer(near the cathode).

Although a film thickness of the hole transporting layer is notparticularly limited, the film thickness is preferably 10 nm to 200 nm.

In the organic EL device according to the exemplary embodiment, a layercontaining an acceptor material may be bonded to a side near the anodeof the hole transporting layer or the first hole transporting layer.With this arrangement, reduction in the drive voltage and manufacturingcosts is expected.

The acceptor material is preferably a compound represented by thefollowing formula (K).

In the formula (K), R₂₁ to R₂₆ may be mutually the same or different andeach independently represent a cyano group, —CONH₂, a carboxyl group or—COOR₂₇ in which R₂₇ represents an alkyl group having 1 to 20 carbonatoms or a cycloalkyl group having 3 to 20 carbon atoms. Among a pair ofR₂₁ and R₂₂, a pair of R₂₃ and R₂₄ and a pair of R₂₅ and R₂₆, one ormore of the pairs may be combined to form a group represented by—CO—O—CO—

Examples of R₂₇ include a methyl group, ethyl group, n-propyl group,isopropyl group, n-butyl group, isobutyl group, t-butyl group,cyclopentyl group and cyclohexyl group.

Although a film thickness of the acceptor material is not particularlylimited, the film thickness is preferably 5 nm to 20 nm.

Electron Injecting⋅Transporting Layer

The electron injection/transport layer helps injection of the electronto the luminescent layer and has a high electron mobility. The electroninjecting layer is provided for adjusting energy level, by which, forinstance, sudden changes of the energy level can be reduced. Theelectron injection/transport layer includes at least one of the electroninjecting layer and the electron transporting layer.

The organic EL device according to this exemplary embodiment preferablyincludes the electron injecting layer between the emitting layer and thecathode, and the electron injecting layer preferably contains anitrogen-containing cyclic derivative as a main component. The electroninjecting layer may serve as the electron transporting layer.

Noted that “as a main component” means that the nitrogen-containingcyclic derivative is contained in the electron injecting layer at acontent of 50 mass % or more.

The electron transporting material for forming the electron injectinglayer is preferably exemplified by an aromatic heterocyclic compoundhaving in the molecule at least one heteroatom (e.g., nitrogen, oxygen,sulfur and phosphorus). Particularly, a nitrogen-containing cyclicderivative is preferable. The nitrogen-containing cyclic derivative ispreferably an aromatic cyclic compound having a nitrogen-containingsix-membered or five-membered ring skeleton.

The nitrogen-containing cyclic derivative is preferably exemplified by anitrogen-containing cyclic metal chelate complex represented by thefollowing formula (B1).

In the formula (B1), R² to R⁷ each independently represent a hydrogenatom, a halogen atom, an oxy group, an amino group, a hydrocarbon grouphaving 1 to 40 carbon atoms, an alkoxyl group, an aryloxy group, analkxoycarbonyl group, or an aromatic heterocyclic group, all of whichmay have a substituent.

Examples of the halogen atom are fluorine, chlorine, bromine and iodine.In addition, examples of the substituted or unsubstituted amino groupinclude an alkylamino group, an arylamino group, and an aralkylaminogroup.

The alkoxycarbonyl group is represented by —COOY′. Examples of Y′ arethe same as the examples of the alkyl group. The alkylamino group andthe aralkylamino group are represented by —NQ¹Q². Examples for each ofQ¹ and Q² are the same as the examples described in relation to thealkyl group and the aralkyl group (i.e., a group obtained bysubstituting a hydrogen atom of an alkyl group with an aryl group), andpreferable examples for each of Q¹ and Q² are also the same as thosedescribed in relation to the alkyl group and the aralkyl group. One ofQ¹ and Q² may be a hydrogen atom. Note that the aralkyl group is a groupobtained by substituting the hydrogen atom of the alkyl group with thearyl group.

The arylamino group is represented by —NAr¹Ar². Examples for each of Ar¹and Ar² are the same as the examples described in relation to thenon-fused aromatic hydrocarbon group. One of Ar¹ and Ar² may be ahydrogen atom.

M in the formula (B1) represents aluminum (Al), gallium (Ga) or indium(In), among which In is preferable.

L in the formula (B1) represents a group represented by a formula (B2)or (B3) below.

In the formula (B2), R⁸ to R¹² each independently represent a hydrogenatom or a hydrocarbon group having 1 to 40 carbon atoms. Adjacent groupsmay form a cyclic structure. The hydrocarbon group may have asubstituent.

In the formula (B3), R¹³ to R²⁷ each independently represent a hydrogenatom or a hydrocarbon group having 1 to 40 carbon atoms. Adjacent groupsmay form a cyclic structure. The hydrocarbon group may have asubstituent.

Examples of the hydrocarbon group having 1 to 40 carbon atomsrepresented by each of R⁸ to R¹² and R¹³ to R²⁷ in the formulae (B2) and(B3) are the same as those of R² to R⁷ in the formula (B1).

Examples of a divalent group formed when adjacent groups of R⁸ to R¹² inthe formula (B2) and adjacent groups of R¹³ to R²⁷ in the formula (B3)form a cyclic structure are a tetramethylene group, pentamethylenegroup, hexamethylene group, diphenylmethane-2,2′-diyl group,diphenylethane-3,3′-diyl group and diphenylpropane-4,4′-diyl group.

The electron transporting layer preferably contains at least one ofnitrogen-containing heterocyclic derivatives respectively represented bythe following formulae (B4) to (B6).

In the formulae (B4) to (B6), R represents a hydrogen atom, aromatichydrocarbon group having 6 to 60 ring carbon atoms, pyridyl group,quinolyl group, alkyl group having 1 to 20 carbon atoms, or alkoxy grouphaving 1 to 20 carbon atoms. n is an integer in a range of 0 to 4.

In the formulae (B4) to (B6), R¹ represents an aromatic hydrocarbongroup having 6 to 60 ring carbon atoms, pyridyl group, quinolyl group,alkyl group having 1 to 20 carbon atoms, or alkoxy group having 1 to 20carbon atoms.

In the formulae (B4) to (B6), R² and R³ each independently represent ahydrogen atom, aromatic hydrocarbon group having 6 to 60 ring carbonatoms, pyridyl group, quinolyl group, alkyl group having 1 to 20 carbonatoms, or alkoxy group having 1 to 20 carbon atoms.

In the formulae (B4) to (B6), L represents an aromatic hydrocarbon grouphaving 6 to 60 ring carbon atoms, pyridinylene group, quinolinylenegroup or fluorenylene group.

In the formulae (B4) to (B6), Ar¹ represents an aromatic hydrocarbongroup having 6 to 60 ring carbon atoms, pyridinylene group orquinolinylene group.

In the formulae (B4) to (B6), Ar² represents an aromatic hydrocarbongroup having 6 to 60 ring carbon atoms, pyridyl group, quinolyl group,alkyl group having 1 to 20 carbon atoms, or alkoxy group having 1 to 20carbon atoms.

In the formulae (B4) to (B6), Ar³ represents an aromatic hydrocarbongroup having 6 to 60 ring carbon atoms, pyridyl group, quinolyl group,alkyl group having 1 to 20 carbon atoms, alkoxy group having 1 to 20carbon atoms, or a group represented by —Ar¹—Ar² (in which Ar¹ and Ar²are the same as those described above).

The aromatic hydrocarbon group, pyridyl group, quinolyl group, alkylgroup, alkoxy group, pyridinylene group, quinolinylene group andfluorenylene group which are described in relation to R, R¹, R², R³, L,Ar¹, Ar² and Ar³ in the formulae (B4) to (B6) may have a substituent.

As an electron transporting compound for the electron injecting layer orthe electron transporting layer, 8-hydroxyquinoline or a metal complexof its derivative, an oxadiazole derivative and a nitrogen-containingheterocyclic derivative are preferable. An example of the8-hydroxyquinoline or the metal complex of its derivative is a metalchelate oxinoid compound containing a chelate of oxine (typically8-quinolinol or 8-hydroxyquinoline). For instance, tris(8-quinolinol)aluminum can be used. Examples of the oxadiazole derivative are asfollows.

In each of the formulae of the oxadiazole derivatives, Ar¹⁷, Ar¹⁸, Ar¹⁹,Ar²¹, Ar²² and Ar²⁵ represent an aromatic hydrocarbon group having 6 to40 ring carbon atoms.

Note that the aromatic hydrocarbon group described herein may have asubstituent. Ar¹⁷, Ar¹⁹ and Ar²² are respectively the same as ordifferent from Ar¹⁸, Ar²¹ and Ar²⁵.

Examples of the aromatic hydrocarbon group described herein are a phenylgroup, naphthyl group, biphenyl group, anthranil group, perylenyl groupand pyrenyl group. Examples of the substituent therefor are an alkylgroup having 1 to 10 carbon atoms, alkoxy group having 1 to 10 carbonatoms and cyano group.

In each of the formulae of the oxadiazole derivatives, Ar²⁰, Ar²³ andAr²⁴ are a divalent aromatic hydrocarbon group having 6 to 40 ringcarbon atoms.

It should be noted that the aromatic hydrocarbon group described hereinmay have a substituent.

Ar²³ and Ar²⁴ are mutually the same or different.

Examples of the divalent aromatic hydrocarbon group described herein area phenylene group, naphthylene group, biphenylene group, anthranylenegroup, perylenylene group and pyrenylene group. Examples of thesubstituent therefor are an alkyl group having 1 to 10 carbon atoms,alkoxy group having 1 to 10 carbon atoms and cyano group.

Such an electron transport compound is preferably an electron transportcompound that can be favorably formed into a thin film(s). Examples ofthe electron transport compound are as follows.

An example of the nitrogen-containing heterocyclic derivative as theelectron transporting compound is a nitrogen-containing compound that isnot a metal complex, the derivative being formed of an organic compoundrepresented by one of the following formulae. Examples of thenitrogen-containing compound are a nitrogen-containing compound havingfive-membered ring or six-membered ring with a skeleton represented bythe following formula (B7) and a nitrogen-containing compound having astructure represented by the following formula (B8).

In the formula (B8), X represents a carbon atom or a nitrogen atom. Z₁and Z₂ each independently represent an atom group from which anitrogen-containing heterocycle can be formed.

More preferably, the nitrogen-containing heterocyclic derivative is anorganic compound having a nitrogen-containing aromatic polycyclic grouphaving a five-membered ring or six-membered ring. Further, in theorganic compound having the nitrogen-containing aromatic polycyclicgroup having plural nitrogen atoms, a nitrogen-containing aromaticpolycyclic organic compound having a skeleton formed by a combination ofthe skeletons respectively represented by the formulae (B7) and (B8), orby a combination of the skeletons respectively represented by theformula (B7) and the following formula (B9) is preferable.

A nitrogen-containing group of the nitrogen-containing aromaticpolycyclic organic compound is selected from nitrogen-containingheterocyclic groups respectively represented by the following formulae.

In each of the formulae of the nitrogen-containing heterocyclic groups,R represents an aromatic hydrocarbon group having 6 to 40 ring carbonatoms, aromatic heterocyclic group having 2 to 40 ring carbon atoms,alkyl group having 1 to 20 carbon atoms, or alkoxy group having 1 to 20carbon atoms.

In each of the formulae of the nitrogen-containing heterocyclic groups,n is an integer of 0 to 5. When n is 2 or more, a plurality of R may bemutually the same or different.

A preferable specific compound is a nitrogen-containing heterocyclicderivative represented by the following formula (B 10).HAr-L¹-Ar¹—Ar²   (B10)

In the above formula (B10), HAr is a nitrogen-containing heterocyclicgroup having 1 to 40 ring carbon atoms.

In the formula (B10), L¹ represents a single bond, an aromatichydrocarbon group having 6 to 40 ring carbon atoms, or an aromaticheterocyclic group having 2 to 40 ring carbon atoms.

In the formula (B 10), Ar¹ is a divalent aromatic hydrocarbon grouphaving 6 to 40 ring carbon atoms.

In the formula (B10), Ar² is an aromatic hydrocarbon group having 6 to40 ring carbon atoms or aromatic heterocyclic group having 2 to 40 ringcarbon atoms.

The nitrogen-containing heterocyclic group, aromatic hydrocarbon groupand aromatic heterocyclic group described in relation to HAr, L¹, Ar¹and Ar² in the formula (B 10) may have a substituent.

HAr in the formula (B 10) is exemplarily selected from the followinggroup.

L¹ in the formula (B10) is exemplarily selected from the followinggroup.

Ar¹ in the formula (B 10) is exemplarily selected from the followingarylanthranil group.

In the formula (A1), R¹ to R¹⁴ each independently represent a hydrogenatom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, analkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to40 ring carbon atoms, an aromatic hydrocarbon group having 6 to 40 ringcarbon atoms, or an aromatic heterocyclic group having 2 to 40 ringcarbon atoms.

In the formula of the arylanthranil group, Ar³ is an aromatichydrocarbon group having 6 to 40 ring carbon atoms or aromaticheterocyclic group having 2 to 40 ring carbon atoms.

The aromatic hydrocarbon group and aromatic heterocyclic group describedin relation to R¹ to R¹⁴ and Ar³ in the formula of the arylanthranil mayhave a substituent.

All of R¹ to R⁸ of a nitrogen-containing heterocyclic derivative may behydrogen atoms.

In the formula of the arylanthranil group, Ar² is exemplarily selectedfrom the following group.

Other than the above, the following compound represented by thefollowing formula (B11) (see JP-A-9-3448) can be favorably used for thenitrogen-containing aromatic polycyclic organic compound as the electrontransporting compound.

In the formula (B11) of the nitrogen-containing aromatic polycyclicorganic compound, R¹ to R⁴ each independently represent a hydrogen atom,aliphatic group, alicyclic group, carbocyclic aromatic cyclic group orheterocyclic group. Note that the aliphatic group, alicyclic group,carbocyclic aromatic cyclic group and heterocyclic group may have asubstituent.

In the formula (B 11) of the nitrogen-containing aromatic polycyclicorganic compound, X¹ and X² each independently represent an oxygen atom,sulfur atom or dicyanomethylene group.

The following compound represented by the following formula (B12) (seeJP-A-2000-173774) can also be favorably used for the electrontransporting compound.

In the formula (B12), R¹, R², R³ and R⁴, which may be mutually the sameor different, each represent an aromatic hydrocarbon group or fusedaromatic hydrocarbon group represented by the following formula (B12-1).

In the formula (B 12-1), R⁵, R⁶, R⁷, R⁸ and R⁹, which may be mutuallythe same or different, each represent a hydrogen atom, a saturated orunsaturated alkoxyl group, alkyl group, amino group or alkylamino group.At least one of R⁵, R⁶, R⁷, R⁸ and R⁹ represents a saturated orunsaturated alkoxyl group, alkyl group, amino group or alkylamino group.

A polymer compound containing the nitrogen-containing heterocyclic groupor a nitrogen-containing heterocyclic derivative may be used for theelectron transporting compound.

Although a film thickness of the electron injecting layer or theelectron transporting layer is not specifically limited, the filmthickness is preferably in a range of 1 nm to 100 nm.

The electron injecting layer preferably contains an inorganic compoundsuch as an insulator or a semiconductor in addition to thenitrogen-containing cyclic derivative. Such an insulator or asemiconductor, when contained in the electron injecting layer, caneffectively prevent a current leak, thereby enhancing electroncapability of the electron injecting layer.

For such an insulator, at least one metal compound selected from a groupof alkali metal chalcogenide, alkaline-earth metal chalcogenide,halogenide of alkali metal, and halogenide of alkaline-earth metal maypreferably be utilized. A configuration in which the electron injectinglayer is formed by these alkali metal chalcogenide and the like isadvantageous in that the electron injecting property is furtherimproved. Specifically, preferable examples of the alkali metalchalcogenide are lithium oxide (Li₂O), potassium oxide (K₂O), sodiumsulfide (Na₂S), sodium selenide (Na₂Se) and sodium oxide (Na₂O).Preferable examples of the alkaline-earth metal chalcogenide are calciumoxide (CaO), barium oxide (BaO), strontium oxide (SrO), beryllium oxide(BeO), barium sulfide (BaS) and calcium selenide (CaSe). Preferableexamples of the halogenide of the alkali metal are lithium fluoride(LiF), sodium fluoride (NaF), potassium fluoride (KF), lithium chloride(LiCl), potassium chloride (KCl) and sodium chloride (NaCl). Preferableexamples of the halogenide of the alkaline-earth metal are fluoridessuch as calcium fluoride (CaF₂), barium fluoride (BaF₂), strontiumfluoride (SrF₂), magnesium fluoride (MgF₂) and beryllium fluoride(BeF₂), and halogenides other than the fluorides.

Examples of the semiconductor are one of or a combination of two or moreof an oxide, a nitride or an oxidized nitride containing at least oneelement selected from barium (Ba), calcium (Ca), strontium (Sr),ytterbium (Yb), aluminum (Al), gallium (Ga), indium (In), lithium (Li),sodium (Na), cadmium (Cd), magnesium (Mg), silicon (Si), tantalum (Ta),antimony (Sb) and zinc (Zn). An inorganic compound for forming theelectron injecting layer is preferably a microcrystalline or amorphousinsulative thin-film. When the electron injecting layer is formed ofsuch an insulative thin-film, more uniform thin-film can be formed,thereby reducing pixel defects such as a dark spot. Examples of such aninorganic compound are the above-described alkali metal chalcogenide,alkaline-earth metal chalcogenide, halogenide of the alkali metal andhalogenide of the alkaline-earth metal.

When the electron injecting layer contains such an insulator or asemiconductor, a film thickness thereof is preferably in a range ofapproximately 0.1 nm to 15 nm. The electron injecting layer according tothe exemplary embodiment may preferably contain the above-describedreductive dopant.

Electron-Donating Dopant and Organic Metal Complex

In the organic EL device according to this exemplary embodiment, atleast one of an electron-donating dopant and an organic metal complex ispreferably contained in an interfacial region between the cathode andthe organic thin-film layer.

With this arrangement, the organic EL device can emit light withenhanced luminance intensity and have a longer lifetime.

The electron-donating dopant may be at least one selected from an alkalimetal, an alkali metal compound, an alkaline-earth metal, analkaline-earth metal compound, a rare-earth metal, a rare-earth metalcompound and the like.

The organic metal complex may be at least one selected from an organicmetal complex including an alkali metal, an organic metal complexincluding an alkaline-earth metal, an organic metal complex including arare-earth metal and the like.

Examples of the alkali metal are lithium (Li) (work function: 2.93 eV),sodium (Na) (work function: 2.36 eV), potassium (K) (work function: 2.28eV), rubidium (Rb) (work function: 2.16 eV) and cesium (Cs) (workfunction: 1.95 eV), which particularly preferably has a work function of2.9 eV or less. Among the above, the reductive dopant is preferably K,Rb or Cs, more preferably Rb or Cs, the most preferably Cs.

Examples of the alkaline-earth metal are calcium (Ca) (work function:2.9 eV), strontium (Sr) (work function: 2.0 to 2.5 eV), and barium (Ba)(work function: 2.52 eV), among which a substance having a work functionof 2.9 eV or less is particularly preferable.

Examples of the rare-earth metal are scandium (Sc), yttrium (Y), cerium(Ce), terbium (Tb), and ytterbium (Yb), among which a substance having awork function of 2.9 eV or less is particularly preferable.

Since the above preferred metals have particularly high reducibility,addition of a relatively small amount of the metals to an electroninjecting zone can enhance luminance intensity and lifetime of theorganic EL device.

Examples of the alkali metal compound are an alkali oxide such aslithium oxide (Li₂O), cesium oxide (Cs₂O) and potassium oxide (K₂O), andan alkali halogenide such as sodium fluoride (NaF), cesium fluoride(CsF) and potassium fluoride (KF), among which lithium fluoride (LiF),lithium oxide (Li₂O) and sodium fluoride (NaF) are preferable.

Examples of the alkaline-earth metal compound are barium oxide (BaO),strontium oxide (SrO), calcium oxide (CaO) and a mixture thereof, i.e.,barium strontium oxide (Ba_(x)Sr_(1-x)O) (0<x<1), barium calcium oxide(Ba_(x)Ca_(1-x)O) (0<x<1), among which BaO, SrO and CaO are preferable.

Examples of the rare earth metal compound are ytterbium fluoride (YbF₃),scandium fluoride (ScF₃), scandium oxide (ScO₃), yttrium oxide (Y₂O₃),cerium oxide (Ce₂O₃), gadolinium fluoride (GdF₃) and terbium fluoride(TbF₃), among which YbF₃, ScF₃, and TbF₃ are preferable.

The organic metal complex is not specifically limited as long ascontaining at least one metal ion of an alkali metal ion, analkaline-earth metal ion and a rare earth metal ion. A ligand for eachof the complexes is preferably quinolinol, benzoquinolinol, acridinol,phenanthridinol, hydroxyphenyl oxazole, hydroxyphenyl thiazole,hydroxydiaryl oxadiazole, hydroxydiaryl thiadiazole, hydroxyphenylpyridine, hydroxyphenyl benzoimidazole, hydroxybenzo triazole, hydroxyfluborane, bipyridyl, phenanthroline, phthalocyanine, porphyrin,cyclopentadiene, â-diketones, azomethines, or a derivative thereof, butthe ligand is not limited thereto.

The electron-donating dopant and the organic metal complex are added topreferably form a layer or an island pattern in the interfacial region.The layer of the electron-donating dopant or the island pattern of theorganic metal complex is preferably formed by evaporating at least oneof the electron-donating dopant and the organic metal complex byresistance heating evaporation while an emitting material for formingthe interfacial region or an organic substance as an electron-injectingmaterial are simultaneously evaporated, so that at least one of theelectron-donating dopant and an organic metal complex reduction-causingdopant is dispersed in the organic substance. Dispersion concentrationat which the electron-donating dopant is dispersed in the organicsubstance is a mole ratio (the organic substance to theelectron-donating dopant or the organic metal complex) of 100:1 to1:100, preferably 5:1 to 1:5.

When at least one of the electron-donating dopant and the organic metalcomplex forms a layer, the emitting material or the electron injectingmaterial for forming the organic layer of the interfacial region isinitially layered, and then, at least one of the electron-donatingdopant and the organic metal complex is singularly evaporated thereon byresistance heating evaporation to preferably form a 0.1 nm- to 15nm-thick layer.

When at least one of the electron-donating dopant and the organic metalcomplex forms an island pattern, the emitting material or the electroninjecting material for forming the organic layer of the interfacialregion is initially layered, and then, at least one of theelectron-donating dopant is singularly evaporated thereon by resistanceheating evaporation to preferably form a 0.05 nm- to 1 nm-thick islandpattern.

A ratio of the main component to at least one of the electron-donatingdopant and the organic metal complex in the organic EL device accordingto the exemplary embodiment is preferably a mole ratio (the maincomponent to the electron-donating dopant or the organic metal complex)of 5:1 to 1:5, more preferably 2:1 to 1:2.

n/p Doping

In the aforementioned hole transporting layer and electron transportinglayer, carrier injectability is adjustable by doping (n) of the donormaterial or doping (p) of the acceptor material as described in thespecification of JP Patent No. 3695714.

n-doping is representatively exemplified by a method of doping a metalsuch as Li or Cs to an electron transporting material. p-doping isrepresentatively exemplified by a method of doping an acceptor materialsuch as F₄TCNQ(2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane) toa hole transporting material.

In the organic EL device according to the exemplary embodiment, inaddition to the above exemplary compounds, any compound used in thetypical organic EL device is usable as a compound for the organicthin-film layer other than the emitting layer (i.e., the hole injectinglayer, hole transporting layer, electron transporting layer, electroninjecting layer and blocking layer).

Formation Method of Each Layer of Organic EL Device

A method of forming each of the layers in the organic EL deviceaccording to the exemplary embodiment is not particularly limited. Aconventionally known method such as vacuum deposition method, sputteringmethod, ink jet method or spin coating method may be employed forforming the layers. The organic thin-film layer containing the compoundused in the organic EL device according to this exemplary embodiment canbe formed by a conventional coating method such as vacuum depositionmethod, molecular beam epitaxy (MBE) method or a coating method with asolution by a dipping method, spin coating method, casting method, barcoating method, ink jet method or roll coating method.

Film Thickness of Each Layer of Organic EL Device

A film thickness of the emitting layer is preferably in a range of 5 nmto 50 nm, more preferably in a range of 7 nm to 50 nm and mostpreferably in a range of 10 nm to 50 nm. By forming the emitting layerat the film thickness of 5 nm or more, the emitting layer is easilyformable and chromaticity is easily adjustable. By forming the emittinglayer at the film thickness of 50 nm or less, increase in the drivevoltage is suppressible.

A film thickness of the organic thin-film layer other than the emittinglayer is not particularly limited, but is preferably in a typical rangeof several nm to 1 μm. When the film thickness is provided in the aboverange, defects such as pin holes caused by an excessively thinned filmcan be avoided while increase in the drive voltage caused by anexcessively thickened film can be suppressed to prevent deterioration ofthe efficiency.

Second Exemplary Embodiment

Next, a second exemplary embodiment is described below.

In the description of the second exemplary embodiment, the samecomponents as those in the first exemplary embodiment are denoted by thesame reference signs and names to simplify or omit an explanation of thecomponents. In the second exemplary embodiment, the same materials andcompounds as described in the first exemplary embodiment are usable.

An organic EL device according to the second exemplary embodiment is aso-called tandem-type device including a charge generating layer and atleast two emitting units. In addition to charges injected from a pair ofelectrodes, charges supplied from the charge generating layer areinjected into the emitting units. Accordingly, by providing the chargegenerating layer, luminous efficiency (current efficiency) relative toinjected current is improved.

As shown in FIG. 3, an organic EL device 1B according to the secondexemplary embodiment is provided by laminating an anode 3, a firstemitting unit 5A, a charge generating layer 20, a second emitting unit5B and a cathode 4 on a substrate 2 in this sequence.

The first emitting unit 5A is provided by laminating a first holetransporting layer 61, first emitting layer 51 and a first electrontransporting layer 71 from the anode 3 in this sequence.

The second emitting unit 5B is provided by laminating a second holetransporting layer 62, second emitting layer 52 and second electrontransporting layer 72 from the charge generating layer 20 in thissequence.

At least one of the first emitting layer 51 and the second emittinglayer 52 is an emitting layer containing the first host material, secondhost material and luminescent material as described above. In theexemplary embodiment, the second emitting layer 52 contains the firsthost material, second host material and the yellow-emittingphosphorescent dopant material (luminescent material) as describedabove. The first emitting layer contains the blue-emitting fluorescentdopant material and the fluorescent host material.

The charge generating layer 20 generates charges when an electric fieldis applied to the organic EL device 1B and injects electrons to thefirst electron transporting layer 71 while injecting holes to the secondhole transporting layer 62.

As a material for the charge generating layer 20, a known material suchas a material described in U.S. Pat. No. 7,358,661 is usable. Specificexamples of the material include oxides, nitrides, iodides and boridesof metals such as In, Sn, Zn, Ti, Zr, Hf, V, Mo, Cu, Ga, Sr, La and Ru.In order that the first emitting layer 51 easily accepts the electronsfrom the charge generation layer 20, it is suitable to dope a donor, arepresentative example of which is an alkali metal, in the vicinity ofan interface of the charge generation layer in the first electrontransporting layer 71. As the donor, at least one of a donor metal,donor metal compound and donor metal complex can be selected. Specificexamples of the compounds used for the donor metal, donor metal compoundand donor metal complex include compounds disclosed in PatentApplication Number PCT/JP2010/003434.

The second hole transporting layer 62 and the second electrontransporting layer 72 are the same as the hole transporting layer andthe electron transporting layer according to the first exemplaryembodiment.

Since the organic EL device 1B is a so-called tandem-type device, thedrive voltage can be reduced and durability can also be improved.

Modifications of Embodiment(s)

It should be noted that the invention is not limited to the aboveexemplary embodiment but may include any modification and improvement aslong as such modification and improvement are compatible with theinvention.

The organic EL device according to the exemplary embodiment may includea hole transporting layer, emitting layer, space layer, blocking layerand the like. The layers may contain the same compounds as the abovecompounds for the first host material and the second host material.

For instance, the organic EL device may further include an electronblocking layer provided to the emitting layer near the anode and a holeblocking layer provided to the emitting layer near the cathode. Withthis arrangement, the electrons and the holes can be trapped in theemitting layer, thereby enhancing probability of exciton generation inthe emitting layer.

The emitting layer is not limited to a single layer, but may be providedby laminating a plurality of emitting layers. When the organic EL devicehas the plurality of emitting layers, it is only required that at leastone of the emitting layers contains the first and second host materials.

Moreover, when the organic EL device includes the plurality of emittinglayers, the plurality of emitting layers may be adjacent to each other,or may be laminated on each other via a layer other than the emittinglayers (e.g., a charge generating layer).

The organic EL device according to the exemplary embodiment may be afluorescent monochromatic emission device or a phosphorescentmonochromatic emission device, or alternatively, may be a white-emittinghybrid device of the fluorescent and phosphorescent monochromaticemission devices. The organic EL device according to the exemplaryembodiment may be in a simple structure having a single emitting unit ormay be in a tandem structure including a plurality of emitting units.Among the above, a phosphorescent monochromatic emission device ispreferable. Herein, the “emitting unit” means the minimum unit thatincludes an organic layer having one or more layers, in which one of thelayers is an emitting layer to emit light by recombination of injectedholes and electrons.

(1) Anode/Emitting Unit/Cathode

The aforementioned emitting unit may be provided by laminating aplurality of phosphorescent-emitting layers and fluorescent-emittinglayers. In this arrangement, a space layer may be provided between theemitting layers in order to prevent excitons generated in thephosphorescent-emitting layers from diffusing into thefluorescent-emitting layers. Representative examples of a layerarrangement of the emitting unit are given below:

(a1) hole transporting layer/emitting layer (/electron transportinglayer);

(b1) hole transporting layer/first phosphorescent-emitting layer/secondphosphorescent-emitting layer (/electron transporting layer);

(c1) hole transporting layer/phosphorescent-emitting layer/spacelayer/fluorescent-emitting layer (/electron transporting layer);

(d1) hole transporting layer/first phosphorescent-emitting layer/secondphosphorescent-emitting layer/space layer/fluorescent-emitting layer(/electron transporting layer);

(e1) hole transporting layer/first phosphorescent-emitting layer/spacelayer/second phosphorescent-emitting layer/spacelayer/fluorescent-emitting layer (/electron transporting layer);

(f1) hole transporting layer/phosphorescent-emitting layer/spacelayer/first fluorescent-emitting layer/second fluorescent-emitting layer(/electron transporting layer);

(g1) hole transporting layer/electron blocking layer/emitting layer(/electron transporting layer);

(h1) hole transporting layer/emitting layer/hole blocking layer(/electron transporting layer); and

(i1) hole transporting layer/fluorescent-emitting layer/triplet blockinglayer (/electron transporting layer).

Each of the phosphorescent-emitting layers or the fluorescent-emittinglayers can exhibit different emission colors. Specifically, the abovelaminated emitting layers (d1) is in the layer arrangement of the holetransporting layer/first phosphorescent-emitting layer (redemission)/second phosphorescent-emitting layer (green emission)/spacelayer/fluorescent-emitting layer (blue emission)/electron transportinglayer.

An electron blocking layer may be provided as needed between each of theemitting layers and the hole transporting layer or the space layer.Moreover, a hole blocking layer may be provided as needed between eachof the emitting layers and the electron transporting layer. Provision ofthe electron blocking layer or the hole blocking layer enables electronsor holes to be trapped in the emitting layers, thereby enhancingprobability of charge recombination in the emitting layers to improveluminous efficiency.

A representative device arrangement of the tandem-type organic EL deviceis shown below.

(2) Anode/First Emitting Unit/Intermediate Layer/Second EmittingUnit/Cathode

Herein, the first emitting unit and the second emitting unit can beindependently the same as the aforementioned emitting units.

The intermediate layer is generally referred to as an intermediateelectrode, intermediate conductive layer, charge generating layer,electron drawing layer, connection layer or intermediate insulativelayer. The intermediate layer can be made of known materials that supplyelectrons to the first emitting unit and holes to the second emittingunit.

Space Layer

For instance, when a fluorescent-emitting layer is laminated to aphosphorescent-emitting layer, the space layer is provided between thefluorescent-emitting layer and the phosphorescent-emitting layer inorder to prevent excitons generated in the phosphorescent-emitting layerfrom diffusing into the fluorescent-emitting layer or to adjust carrierbalance. Moreover, the space layer may be provided between a pluralityof phosphorescent-emitting layers.

Since the space layer is provided between the emitting layers, the spacelayer is preferably formed of a material having both of electrontransporting capability and hole transporting capability. Moreover,triplet energy of the space layer is preferably 2.6 eV or more in orderto prevent diffusion of triplet energy into an adjacentphosphorescent-emitting layer. The material used for the space layer isthe same as the aforementioned material used for the hole transportinglayer.

Blocking Layer

The organic EL device according to the exemplary embodiment preferablyincludes a blocking layer such as an electron blocking layer, holeblocking layer or triplet blocking layer at a part adjacent to theemitting layer. Herein, the electron blocking layer prevents electronsfrom leaking from the emitting layer into the hole transporting layerwhile the hole blocking layer prevents holes from leaking from theemitting layer into the electron transporting layer.

The triplet blocking layer has a function of preventing triplet excitonsgenerated in the emitting layer from diffusing into neighboring layersto trap the triplet excitons within the emitting layer, therebysuppressing energy deactivation of the triplet excitons on moleculesother than the emitting dopant in the electron transporting layer.

When the triplet blocking layer is provided in a phosphorescent device,supposing that triplet energy of a phosphorescent dopant in the emittinglayer is denoted as E^(T) _(d) and triplet energy of a compound used asthe triplet blocking layer is denoted as E^(T) _(TB), in an energyrelationship of E^(T) _(d)<E^(T) _(TB), triplet excitons of thephosphorescent dopant are trapped (cannot be transferred to anothermolecule) due to the energy relationship to leave no alternative routefor energy deactivation other than emission on the dopant, so thathighly efficient emission can be expected. However, when an energy gap(ΔE^(T)=E^(T) _(TB)−E^(T) _(d)) is small even though the relationship ofE^(t) _(d)<E^(T) _(TB) is satisfied, under actual environments fordriving a device (i.e., at around the room temperature), it isconsidered that triplet excitons can be transferred to another moleculeirrespective of the energy gap ΔE^(T) by absorbing ambient heat energy.Particularly, since the excitons of the phosphorescent device have alonger lifetime than those of a fluorescent device, influence by heatabsorption during transfer of the excitons is more likely to emerge onthe phosphorescent device relative to the fluorescent device. The largerenergy gap ΔE^(T) relative to the heat energy at the room temperature ispreferable, more preferably 0.1 eV or more, particularly preferable at0.2 eV or more.

An electron mobility of a material for forming the triplet blockinglayer is desirably 10⁻⁶ cm²/Vs or more in an electric field intensity of0.04 MV/cm to 0.5 MV/cm. As a measuring method of the electron mobilityof the organic material, some methods such as Time of Flight method areknown. Herein, the electron mobility is determined by the impedancespectroscopy.

An electron mobility of a material for forming the electron injectinglayer is desirably 10⁻⁶ cm²/Vs or more in the electric field intensityof 0.04 MV/cm to 0.5 MV/cm. This arrangement promotes electron injectionfrom the cathode to the electron transporting layer, thereby promotingthe electron injection to the neighboring blocking layer and emittinglayer, so that the device can be driven at a low voltage.

EXAMPLES

Next, the present invention will be described in further detail byexemplifying Example(s) and Comparative(s). However, the presentinvention is not limited by the description of Example(s).

Synthesis of Compounds Synthesis Example 1-1 Synthesis of Compound H1-1Synthesis Example 1-1-1 Synthesis of Intermediate Body 1-1

Under argon, to a 1000-mL eggplant flask, carbazole (56 g, 334 mmol) andN,N-dimethylformamide (250 mL) were added and cooled to −7 degrees C. inan ice water bath (in which sodium chloride was added). To the mixture,a solution (200 mL) of N-bromosuccinimide (119 g, 668 mmol) inN,N-dimethylformamide was dropped and stirred for four hours at −7degrees C.

The reaction solution was added with pure water to be heated to the roomtemperature. Subsequently, a precipitated solid was collected byfiltration. The obtained solid was repeatedly recrystallized in toluene,so that an intermediate body 1-1 (71 g, a yield rate of 65%) wasobtained. As a result of FD-MS (Field Desoprtion Mass Spectrometry)analysis, the reactant was identified as the intermediate body 1-1.

Synthesis Example 1-1-2 Synthesis of Intermediate Body 1-2

Under argon, to a 2000-mL eggplant flask, the intermediate body 1-1 (33g, 102 mmol), phenylboronic acid (27 g, 221 mmol),tetrakis(triphenylphosphine)palladium (7.0 g, 6.1 mmol),1,2-dimethoxyethane (600 mL) and 2M sodium carbonate solution (200 mL)were sequentially added and heated to reflux for eight hours.

After the reaction solution was cooled down to the room temperature, anorganic phase was separated and an organic solvent was distilled awayunder reduced pressure. The obtained residue was refined by silica-gelcolumn chromatography, whereby an intermediate body 1-2 (19 g, a yieldrate of 58%) was obtained. As a result of FD-MS (Field Desoprtion MassSpectrometry) analysis, the reactant was identified as the intermediatebody 1-2.

Synthesis Example 1-1-3 Synthesis of Intermediate Body 1-3

An intermediate body 1-3 was synthesized by the same method as theintermediate body 1-2 except that 2,4,6-trichloropyrimidine was used inplace of the intermediate body 1-1. As a result of FD-MS (FieldDesoprtion Mass Spectrometry) analysis, the reactant was identified asthe intermediate body 1-3.

Synthesis Example 1-1-4 Synthesis of Intermediate Body 1-4

An intermediate body 1-4 was synthesized by the same method as theintermediate body 1-2 except that the intermediate body 1-3 was used inplace of the intermediate body 1-1 and that4′-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)biphenyl-4-carbonitrilewas used in place of phenylboronic acid. As a result of FD-MS (FieldDesoprtion Mass Spectrometry) analysis, the reactant was identified asthe intermediate body 1-4.

Synthesis Example 1-1-5 Synthesis of Compound H1-1

Under argon, the intermediate body 1-2 (2.3 g, 7.2 mmol), theintermediate body 1-4 (3.2 g, 8.6 mmol),tris(dibenzylideneacetone)dipalladium (0.26 g, 0.29 mmol),tri-t-butylphosphonium tetrafluoroborate (0.21 g, 0.72 mmol), sodiumt-butoxide (1.4 g, 14 mmol), and anhydrous xylene (40 mL) weresequentially added, and heated to reflux for eight hours.

After the reaction solution was cooled down to the room temperature, anorganic phase was separated and an organic solvent was distilled awayunder reduced pressure. The obtained residue was refined by silica-gelcolumn chromatography, whereby 3.6 g of a yellowish white solid (H1-1)was obtained.

A result of FD-MS (Field Desoprtion Mass Spectrometry) of the obtainedcompound and a maximum fluorescent wavelength thereof in a toluenesolution FL(PhMe, λex=325 nm; λmax) are shown below:

FDMS, calcd for C47H30N4=650, found m/z=650 (M+)

FL(PhMe, λex=325 nm); λmax, 471 nm

Synthesis Example 1-2 Synthesis of Compound H1-2 Synthesis Example 1-2-1Synthesis of Intermediate Body 1-5

Under argon, 2-nitro-1,4-dibromobenzene (11.2 g, 40 mmol), phenylboronicacid (4.9 g, 40 mmol), tetrakis(triphenylphosphine)palladium (1.39 g,1.2 mmol), toluene (120 mL) and an aqueous solution of 2M sodiumcarbonate (60 mL) were sequentially added and heated to reflux for eighthours.

After the reaction solution was cooled down to the room temperature, anorganic phase was separated and an organic solvent was distilled awayunder reduced pressure. The obtained residue was refined by silica-gelcolumn chromatography, so that an intermediate body 5 (6.6 g, a yield of59%) was obtained. As a result of FD-MS (Field Desoprtion MassSpectrometry) analysis, the reactant was identified as the intermediatebody 1-5.

Synthesis Example 1-2-2 Synthesis of Intermediate Body 1-6

Under argon, the intermediate body 1-5 (6.6 g, 23.7 mmol),triphenylphosphine (15.6 g, 59.3 mmol), and o-dichlorobenzene (24 mL)were sequentially added and heated to reflux at 180 degrees C. for eighthours.

After cooled down to the room temperature, the reaction solution wasrefined by silica-gel column chromatography, whereby an intermediatebody 6 (4 g, a yield of 68%) was obtained. As a result of FD-MS (FieldDesoprtion Mass Spectrometry) analysis, the reactant was identified asthe intermediate body 1-6.

Synthesis Example 1-2-3 Synthesis of Intermediate Body 1-7

An intermediate body 1-7 was synthesized by the same method as theintermediate body 1-5 except that the intermediate body 1-6 was used inplace of 2-nitro-1,4-dibromobenzene and that9-phenyl-9H-carbazole-3-ylboronic acid was used in place ofphenylboronic acid. As a result of FD-MS (Field Desoprtion MassSpectrometry) analysis, the reactant was identified as the intermediatebody 1-7.

Synthesis Example 1-2-4 Synthesis of Compound H1-2

The compound H1-2 was synthesized by the same method as the compound H-1except that the intermediate body 1-7 was used in place of intermediatebody 1-2.

A result of FD-MS (Field Desoprtion Mass Spectrometry) of the obtainedcompound and a maximum fluorescent wavelength thereof in a toluenesolution FL(PhMe, λex=325 nm; λmax) are shown below:

FDMS, calcd for C53H33N5=739, found m/z=739 (M+)

FL(PhMe, λex=325 nm); λmax, 475 nm

Synthesis Example 1-3 Synthesis of Compound H1-3 Synthesis Example 1-3-1Synthesis of Intermediate Body 1-8

An intermediate body 1-8 was synthesized by the same method as thecompound H1-1 except that carbazole was used in place of intermediatebody 1-2 and 1-bromo-4-iodobenzene was used in place of intermediatebody 1-4. As a result of FD-MS (Field Desoprtion Mass Spectrometry)analysis, the reactant was identified as the intermediate body 1-8.

Synthesis Example 1-3-2 Synthesis of Intermediate Body 1-9

Under argon, the intermediate body 1-8 (8.4 g, 25 mmol),bis(pinacolato)diboron (8.3 g, 33 mmol),[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) dichloridedichloromethane adduct (0.62 g, 0.75 mmol), potassium acetate (7.4 g, 75mmol) and N,N-dimethylformamide (170 mL) were sequentially added, andheated to reflux for eight hours.

After the reaction solution was cooled down to the room temperature, anorganic phase was separated and an organic solvent was distilled awayunder reduced pressure. The obtained residue was refined by silica-gelcolumn chromatography, whereby an intermediate body 1-9 (5.5 g, a yieldof 60%) was obtained. As a result of FD-MS (Field Desoprtion MassSpectrometry) analysis, the reactant was identified as the intermediatebody 1-9.

Synthesis Example 1-3 Synthesis of Compound H1-3

The compound H1-2 was synthesized by the same method as the compoundH1-1 except that the intermediate body 1-9 was used in place ofintermediate body 1-2.

A result of FD-MS (Field Desoprtion Mass Spectrometry) of the obtainedcompound and a maximum fluorescent wavelength thereof in a toluenesolution FL(PhMe, λex=300 nm; λmax) are shown below:

FDMS, calcd for C41H16N4=574, found m/z=574 (M+)

FL(PhMe, λex=300 nm); λmax, 416 nm

Synthesis Example 2-1 Synthesis of Compound H2-1 Synthesis Example 2-1-1Synthesis of Intermediate Body 2-1

Under argon, to a 2000-mL eggplant flask, 3-bromocarbazole (43 g, 174mmol), 9-phenylcarbazole-3-ylboronic acid (50 g, 174 mmol),[1,1′-bix(diphenylphosphino)ferrocene]palladium(II) dichloridedichloromethane adduct (1.4 g, 1.7 mmol), dioxane (610 mL) and 2M sodiumcarbonate solution (260 mL) were sequentially added and heated to refluxfor eight hours.

After the reaction solution was cooled down to the room temperature, anorganic phase was separated and an organic solvent was distilled awayunder reduced pressure. The obtained residue was refined by silica-gelcolumn chromatography, so that an intermediate body 4 (43 g, a yield of60%) was obtained. As a result of FD-MS (Field Desoprtion MassSpectrometry) analysis, the reactant was identified as the intermediatebody 2-1.

Synthesis Example 2-1-2 Synthesis of Compound H2-1

Under argon, to a 300-mL eggplant flask, the intermediate body 2-1 (5.14g, 12.6 mmol), 4′-bromobiphenyl-4-carbonitrile (3.90 g, 15.1 mmol),tris(dibenzylideneacetone)dipalladium (0.462 g, 0.505 mmol),tri-t-butylphosphonium tetrafluoroborate (0.470 g, 1.62 mmol), sodiumt-butoxide (2.42 g, 25.2 mmol), and anhydrous xylene (25 mL) weresequentially added and heated to reflux for eight hours.

After the reaction solution was cooled down to the room temperature, anorganic phase was separated and an organic solvent was distilled awayunder reduced pressure. The obtained residue was refined by silica-gelcolumn chromatography, whereby 4.5 g of a white solid (H2-1) wasobtained.

A result of FD-MS (Field Desoprtion Mass Spectrometry) of the obtainedcompound, a maximum ultraviolet absorption wavelength thereof in atoluene solution UV(PhMe; λmax) and a maximum fluorescent wavelengththereof in a toluene solution FL(PhMe, λex=310 nm; λmax) are shownbelow:

FDMS, calcd for C43H27N3=585, found m/z=585 (M+)

UV(PhMe); λmax, 340 nm

FL(PhMe, λex=310 nm); λmax, 424 nm

Synthesis Example 2-2 Synthesis of Compound H2-2

The compound H2-2 was synthesized by the same method as the compoundH2-1 except that 4-bromobenzonitrile was used in place of4′-bromobiphenyl-4-carbonitrile.

A result of FD-MS (Field Desoprtion Mass Spectrometry) of the obtainedcompound, a maximum ultraviolet absorption wavelength thereof in atoluene solution UV(PhMe; λmax) and a maximum fluorescent wavelengththereof in a toluene solution FL(PhMe, λex=300 nm; λmax) are shownbelow:

FDMS, calcd for C37H23N3=509, found m/z=509 (M+)

UV(PhMe); λmax, 339 nm

FL(PhMe, λex=300 nm); λmax, 404 nm

Manufacture and Evaluation on Luminescent Performance of Organic ELDevice Example 1 Manufacture of Organic EL Device

A glass substrate (size: 25 mm×75 mm×1.1 mm thick) having an ITOtransparent electrode (manufactured by GEOMATEC Co., Ltd.) wasultrasonic-cleaned in isopropyl alcohol for five minutes, and thenUV/ozone-cleaned for 30 minutes. A film thickness of ITO transparentelectrode was 77 nm.

After the glass substrate having the transparent electrode line wascleaned, the glass substrate was mounted on a substrate holder of avacuum deposition apparatus. The following electron accepting (acceptor)compound (C-1) was evaporated to form a 5-nm thick film of the compoundC-1 on a surface of the glass substrate where the transparent electrodeline was provided so as to cover the transparent electrode.

On the film of the compound C-1, the following aromatic amine derivative(compound X-1) was evaporated as a first hole transporting material toform a 65-nm thick first hole transporting layer.

After film formation of the first hole transporting layer, the followingaromatic amine derivative (compound X-2) was evaporated as a second holetransporting material to form a 10-nm thick second hole transportinglayer.

Further, on the second hole transporting layer, the following compoundH1-1, the following compound H2-1 as the second host material and thefollowing compound Ir(bzq)₃ were co-evaporated to form a 25-nm thickemitting layer. In the emitting layer, concentrations of the compoundIr(bzq)₃, the host material H1-1 and the host material H2-1 wererespectively 10.0 mass %, 45.0 mass % and 45.0 mass %. Thisco-evaporated film serves as the emitting layer.

After the film formation of the emitting layer, a 35-nm thick film ofthe following compound (ET) was formed. The film of the compound ETserves as the electron transporting layer.

Next, a 1-nm thick film of LiF was formed as an electron-injectingelectrode (cathode) at a film-forming speed of 0.1 Å/min. A metal Al wasevaporated on the LiF film to form an 80-nm thick metal cathode.

Thus, an organic EL device of Example 1 was manufactured.

Compounds used in Examples and Comparatives will be shown below.

An arrangement of the organic EL devices manufactured in Examples andComparatives are shown in Table 1. The numerals without a unit inparentheses in Table 1 indicate a thickness of each layer (unit: nm).The numerals with % indicate a mass % concentration of the compound.

TABLE I Arrangement of Organic EL device Example 1ITO(77)/C-1(5)/X-1(65)/X-2(10)/H1-1:H2-1:Ir(bzq)₃(25,45%:45%:10%)/ET(35)/LiF(1)/Al(80) Example 2ITO(77)/C-1(5)/X-1(65)/X-2(10)/H1-2:H2-1:Ir(bzq)₃(25,45%:45%:10%)/ET(35)/LiF(1)/Al(80) Example 3ITO(77)/C-1(5)/X-1(65)/X-3(10)/H1-3:H2-2:Ir(bzq)₃(25,45%:45%:10%)/ET(35)/LiF(1)/Al(80) Comp. 1ITO(77)/C-1(5)/X-1(65)/X-3(10)/F1:Ir(bzq)₃(25, 10%)/ET(35)/LiF(1)/Al(80)Comp. 2 ITO(77)/C-1(5)/X-1(65)/X-3(10)/F2:Ir(bzq)₃(25,10%)/ET(35)/LiF(1)/Al(80) Comp. 3ITO(77)/C-1(5)/X-1(65)/X-3(10)/F1:F2:Ir(bzq)₃(25,45%:45%:10%)/ET(35)/LiF(1)/Al(80) Ref. 1ITO(77)/C-1(5)/X-1(65)/X-3(10)/H1-2:Ir(bzq)₃(25,10%)/ET(35)/LiF(1)/Al(80) Ref. 2ITO(77)/C-1(5)/X-1(65)/X-2(10)/F1:H1-1:Ir(bzq)₃(25,45%:45%:10%)/ET(35)/LiF(1)/Al(80) Ref. 3ITO(77)/C-1(5)/X-1(65)/X-2(10)/F2:H1-2:Ir(bzq)₃(25,45%:45%:10%)/ET(35)/LiF(1)/Al(80)

Examples 2 to 3, Comparatives 1 to 3 and References 1 to 3

Organic EL devices of Examples 2 to 3, Comparatives 1 to 3 andReferences 1 to 3 were manufactured in the same manner as in the Example1 except for using the arrangement of the organic EL device shown inTable 1.

Evaluation of Organic EL Device

The prepared organic EL devices were evaluated in terms of a drivevoltage, an external quantum efficiency EQE and a lifetime LT₉₅. Theresults are shown in Table 2.

Drive Voltage

Electrical current was applied between ITO and Al such that a currentdensity was 10 mA/cm², where voltage (unit: V) was measured.

External Quantum Efficiency EQE

Voltage was applied on each of the organic EL devices at the roomtemperature such that a current density was 10 mA/cm², where EL emissionspectrum was measured by a spectroradiometer (CS-1000 manufactured byKonica Minolta Holdings, Inc.). The external quantum efficiency EQE(unit: %) was calculated based on the obtained spectral-radiancespectra, assuming that the spectra was provided under a Lambertianradiation.

Lifetime

A 95%-lifetime at the current density of 50 mA/cm² was obtained. The95%-lifetime means an elapsed time until a luminance intensity isreduced to 95% of an initial luminance intensity when each of theorganic devices is driven at a constant current. The 95%-lifetime isoccasionally referred to as LT95.

TABLE 2 Host material of Emitting Voltage (V) EQE (%) LT95 (hrs) layer10 (mA/cm²) 10 (mA/cm²) 50 (mA/cm²) Example 1 H1-1:H2-1 3.4 17.9  80Example 2 H1-2:H2-1 3.4 16.6 130 Example 3 H1-3:H2-2 3.1 14.3  80 Comp.1 Fl 3.4 16.8   5 Comp. 2 F2 4.1  6.8   1 Comp. 3 F1:F2 3.4 17.8  20Ref. 1 H1-2 3.2 14.8  70 Ref. 2 F1:H1-2 3.4 18.1  10 Ref. 3 F2:H1-1 3.217.8  40

As understood from Table 2, the organic EL devices of Examples 1 to 3were equal to each other in terms of the luminous efficiency (externalquantum efficiency EQE) and had a prolonged lifetime, as compared withthe organic EL devices of Comparatives 1 to 3.

This is considered to be because the organic EL devices of Examples 1 to3 contained a combination of the first host material (the compoundsH1-1, H1-2, H1-3) having the partial structure represented by theformula (1) and the second host material (the compounds H2-1, H2-2)having the partial structure represented by the formula (3) as the hostmaterial (co-host) of the emitting layer.

On other hand, the organic EL devices of Comparatives 1 to 3 containedthe compound F1 having no partial structure represented by the formula(1) and the compound F2 having no partial structure represented by theformula (3). The organic EL device of Comparative 1 singularly used thecompound F1 and the organic EL device of Comparative 2 singularly usedthe compound F2. Both of the organic EL devices had an extremely shortlifetime.

Further, even when the compounds F1 and F2 were used in combination asthe host material in the emitting layer as shown in Comparative 3, thelifetime of the device was found to be short. The compound F1 and thecompound H-1 as the first host material of Example 1 were similar toeach other in skeleton except for the presence of a cyano group. Thecompound F2 and the compound H2-1 as the second host material of Example1 were similar to each other in skeleton except for the presence of acyano group. However, as described above, since the first host materialand the second host material had specific partial structures, thelifetime of the organic EL device of Example 1 exhibited 80 hours, whichwas four times longer than the lifetime (20 hours) of the organic ELdevice of Comparative 3 using a combination of the compounds having nospecific partial structure.

Reference 1 singularly used the compound H1-2 of the first host materialof Example 2 as the host material. The lifetime of the organic EL deviceof Example 2 was about twice longer than the lifetime of the organic ELdevice of Reference 1.

Reference 2 shows the emitting layer in which the compound H1-2 used asthe first host material of Example 2 and the compound F1 used inComparative 1. The lifetime of the organic EL device of Reference 2 wastwice longer than the lifetime of the organic EL device ofComparative 1. However, the lifetime of the organic EL device ofReference 2 was shorter than the lifetime of the organic EL device ofExample 2.

Reference 3 shows the emitting layer in which the compound H1-1 used asthe first host material of Example 1 and the compound F2 used inComparative 2. The lifetime of the organic EL device of Reference 3 wastwice longer than the lifetime of the organic EL device of Comparative3. However, the lifetime of the organic EL device of Reference 3 washalf of the lifetime of the organic EL device of Example 1.

When two host materials of the emitting layer respectively had thepartial structure represented by the formula (1) and the partialstructure represented by the formula (3) as shown in Examples 1 to 3, itwas found that an advantage of prolonging the lifetime becameremarkable.

In comparison between Examples 1 and 2, when the skeleton of the firsthost material was changed from the carbazole skeleton as in the compoundH1-1 to the biscarbazole skeleton as in the compound H1-2, it was foundthat the lifetime was further prolonged.

Examples 4 to 6

In Examples 4 to 6, the following compounds were used in addition to theabove compounds.

Synthesis of Compounds Synthesis Example 3-1 Synthesis of Compound PG-1

(3-1-1) Synthesis of 2,4-dichloro-6-phenylpyrimidine

Under argon, 2,4,6-trichloropyrimidine (7.28 g, 40 mmol), phenylboronicacid (4.9 g, 40 mmol), tetrakis(triphenylphosphine)palladium (1.39 g,1.2 mmol), toluene (120 mL) and an aqueous solution of 2M sodiumcarbonate (60 mL) were sequentially added and heated to reflux for eighthours.

After the reaction solution was cooled down to the room temperature, anorganic phase was separated and an organic solvent was distilled awayunder reduced pressure. The obtained residue was refined by silica-gelcolumn chromatography, so that 2,4-dichloro-6-phenylpyrimidine (5.4 g)was obtained.

(3-1-2) Synthesis of 2-chloro-4-(3-cyanophenyl)-6-phenylpyrimidine

2-chloro-4-(3-cyanophenyI)-6-phenylpyrimidine was synthesized by thesame method as in syntheses of 2,4-dichloro-6-phenylpyrimidine in theabove (3-1-1), except that 2,4-dichloro-6-phenylpyrimidine was used inplace of 2,4,6-trichloropyrimidine and that 3-cyanophenylboronic acidwas used in place of phenylboronic acid.

(3-1-3) Synthesis of PG-1

Under argon, 2-chloro-4-(3-cyanophenyl)-6-phenylpyrimidine (2.91 g, 10mmol), 3-(9-phenylcarbazole-3-yl)carbazole (4.9 g, 12 mmol) synthesizedby a known method, tris(dibenzylideneacetone)dipalladium (0.183 g, 0.20mmol), tri-t-butylphosphonium tetrafluoroborate (0.15 g, 0.52 mmol),sodium t-butoxide (1.9 g, 20 mmol), and anhydrous xylene (50 mL) weresequentially added and heated to reflux for eight hours.

After the reaction solution was cooled down to the room temperature, anorganic phase was separated and an organic solvent was distilled awayunder reduced pressure. The obtained residue was refined by silica-gelcolumn chromatography, whereby 3.3 g of a compound PG-1 was obtained. Asa result of mass spectrum (FD-MS) analysis, the obtained compound wasthe target compound PG-1 at m/e=663 to 663.24 of a molecular weight.

Synthesis Example 3-2 Synthesis of Compound PG-2

(3-2-1) Synthesis of 4-bromo′-cyanobiphenyl

4-bromo-4′-cyanobiphenyl was synthesized by the same method as insyntheses of 2,4-dichloro-6-phenylpyrimidine in the above (3-1-1),except that 4-bromoiodobenzene was used in place of2,4,6-trichloropyrimidine and that 4-cyanophenylboronic acid was used inplace of phenylboronic acid.

(3-2-2) Synthesis of PG-2

The compound PG-2 was synthesized by the same method as the compoundPG-1 in the above (3-1-3) except that7,7-dimethyl-7H-indeno[2,1-b]carbazole synthesized by a known method wasused in place of 3-(9-phenylcarbazole-3-yl)carbazole and4-bromo-4′-cyanobiphenyl was used in place of2-chloro-4-(3-cyanophenyl)-6-phenylpyrimidine. As a result of massspectrum (FD-MS) analysis, the obtained compound was the target compoundPG-2 at m/e=460 to 460.19 of a molecular weight.

Synthesis Example 3-3 Synthesis of Compound PG-4

(3-3-1) Synthesis of 4,6-bis(trimethylsilyl)dibenzothiophene

Under an argon atmosphere, tetramethylethylenediamine (1.76 kg) andhexane (7.67 L) were prepared, to which a solution (9.51 L) of 1.6Mn-butyllithium in hexane was dropped with stirring at 0 degree C. Afterstirring for 30 minutes at the room temperature, hexane (11.5 L) wasadded and, then, dibenzothiophene (930 g) was added. The temperature ofthe reaction solution was raised to 60 degrees C. and the reactionsolution was stirred for two hours. The reaction solution was cooled to−78 degrees C., to which chlorotrimethylsilane (1.65 kg) was dropped.After stirred for 30 minutes at −78 degrees C., the reaction solutionwas kept stirred for five hours while the temperature of the reactionsolution being raised to the room temperature. A 5%-aqueous solution ofhydrochloric acid (15 L) was added to the reaction solution to quenchthe reaction. After an aqueous phase was removed, an organic phase waswashed with water, dried with magnesium sulfate and distilled away underreduced pressure. The obtained residue was refined by silica-gel columnchromatography, so that 4,6-bis(trimethylsilyl)dibenzothiophene (547 g)was obtained.

(3-3-2) Synthesis of 4,6-dibromodibenzothiophene

4,6-bis(trimethylsilyl)dibenzothiophene (540 g) and chloroform (3.4 L)were prepared, to which a solution (1.4 L) of bromine (551 g) inchloroform was added with stirring at −15 degree C. After stirred for 1hour at −15 degrees C., the reaction solution was kept stirred while thetemperature of the reaction solution being raised to the roomtemperature. The reaction was quenched with a 5%-aqueous solution ofsodium hydroxide (1.4 L). After an aqueous phase was removed, an organicphase was washed with water and dried with magnesium sulfate anddistilled away under reduced pressure. After washed with methanol, theobtained solid was repeatedly recrystallized in toluene to provide4,6-dibromodibenzothiophene (180 g).

(3-3-3) Synthesis of 6-dibromodibenzofuran-4-carboxyaldehyde

Under an argon atmosphere, 4,6-dibromodibenzothiophene (180 g) anddehydrated THF (3.6 L) were prepared, to which a solution (432 mL) of1.6M n-butyllithium in hexane was dropped with stirring at −78 degree C.After stirring the reaction solution for one hour at the roomtemperature, N,N-dimethlformamide (115 g) was added to the reactionsolution. After stirring the reaction solution for 30 minutes at −78degrees C., the temperature of the reaction solution was raised to −40degrees C. and a 5% aqueous solution of hydrochloric acid was added tothe reaction solution to quench the reaction. After an aqueous phase wasremoved, an organic phase was washed with water, dried with magnesiumsulfate and distilled away under reduced pressure. The obtained residuewas refined by silica-gel column chromatography, so that6-bromodibenzofuran-4-carboxyaldehyde (65 g) was obtained.

(3-3-4) Synthesis of 6-cyano-4-bromodibenzothiophene

Under an argon atmosphere, 6-bromodibenzofuran-4-carboxyaldehyde (65 g),hydroxylamine hydrochloride (20.2 g) and NMP (N-methylpyrrolidone) (850mL) were prepared and heated at 150 degrees for 27 hours with stirring.The reaction solution was cooled to the room temperature and added withice water to precipitate crystals. The precipitated crystals werefiltrated. The obtained solid was refined by silica-gel columnchromatography, so that 6-cyano-4-bromodibenzothiophene (34 g) wasobtained.

(3-3-5) Synthesis of 2-(3-bromophenyl)triphenylene

Under an argon atmosphere, triphenylene-2-boronic acid (32.6 g),3-bromoiodobenzene (28.1 g), tetrakistriphenylphosphinepalladium(0)(2.31 g), toluene (200 mL), DME (dimethylether) (200 mL) and an aqueoussolution of 2M sodium carbonate (200 mL) were put in a flask and heatedto reflux for 24 hours. After the reaction solution was cooled down tothe room temperature, the reaction solution was extracted with toluene.After an aqueous phase was removed, an organic layer was washed withsaturated saline. After the organic phase was drided with magnesiumsulfate and concentrated, the obtained residue was refined by silica-gelcolumn chromatography, so that 2-(3-bromophenyl)triphenylene (27.5 g)was obtained.

(3-3-6) Synthesis of 3-(2-triphenylenyl)phenylboronic acid

Under an argon atmosphere, 2-(3-bromophenyl)triphenylene (19.1 g) andtetrahydrofuran (dehydrated) (500 mL) were added to a flask and cooledto −78 degrees C. n-BuLi (1.60M in hexane) (34 mL) was added to theflask. The reaction solution was stirred for two hours while thetemperature of the reaction solution being raised to 0 degree C. Next,the reaction solution was again cooled down to −78 degrees C., addedwith B(OMe)₃ (28.2 g) and stirred for 10 minutes at −78 degrees C.Subsequently, the reaction solution was stirred for five hours while thetemperature of the reaction solution being gradually raised to the roomtemperature.

After the reaction was finished, the reaction solution was added with anaqueous solution of 1N HCl (200 mL) and stirred for one hour at the roomtemperature. Subsequently, the reaction solution was transferred into aseparating funnel and extracted with ethyl acetate.

After the solution was drided with magnesium sulfate, concentrated andwashed with hexane, 3-(2-triphenylenyl)phenylboronic acid (10.4 g) wasobtained.

(3-3-7) Synthesis of PG-4

Under an argon atmosphere, 6-cyano-4-bromodibenzothiophene (2.88 g),3-(2-triphenylenyl)phenylboronic acid (3.83 g),tetrakis(triphenylphosphine)palladium(0) (0.231 g), 1,2-dimethoxyethane(20 mL), toluene (20 mL) and an aqueous solution of 2M sodium carbonate(20 mL) were prepared and refluxed for eight hours. After the reactionsolution was cooled down to the room temperature, a precipitated solidwas filtrated. After washed with water and methanol, the obtained solidwas again recrystallized in toluene to provide the compound PG-1 (4.10g). As a result of mass spectrum (FD-MS) analysis, the obtained compoundwas the target compound PG-4 at m/e=511 to 511.14 of a molecular weight.

Synthesis Example 3-4 Synthesis of Compound PG-5

(3-4-1) Synthesis of 2-chloro-4-(4-cyanophenyl)-6-phenylpyrimidine

2-chloro-4-(3-cyanophenyl)-6-phenylpyrimidine was synthesized by thesame method as in syntheses of 2,4-dichloro-6-phenylpyrimidine in theabove (4-1-1), except that 2,4-dichloro-6-phenylpyrimidine was used inplace of 2,4,6-trichloropyrimidine and that 3-cyanophenylboronic acidwas used in place of phenylboronic acid.

(3-4-2) Synthesis of PG-5

The compound PG-5 was synthesized by the same method as the compoundPG-1 in the above (3-1-3) except that 2-(9-phenylcarbazol-3-yl)carbazolesynthesized by a known method was used in place of3-(9-phenylcarbazole-3-yl)carbazole and2-chloro-4-(4-cyanophenyl)-6-phenylpyrimidine was used in place of2-chloro-4-(3-cyanophenyl)-6-phenylpyrimidine. As a result of massspectrum (FD-MS) analysis, the obtained compound was the target compoundPG-5 at m/e=663 to 663.24 of a molecular weight.

Synthesis Example 3-5 Synthesis of Compound PG-6

The compound PG-6 was synthesized by the same method as the compoundPG-1 in the above (3-1-3) except that11-phenyl-11H,12H-indolo[2,3-a]carbazole synthesized by a known methodwas used in place of 3-(9-phenylcarbazole-3-yl)carbazole and4-bromobenzonitrile was used in place of2-chloro-4-(3-cyanophenyl)-6-phenylpyrimidine. As a result of massspectrum (FD-MS) analysis, the obtained compound was the target compoundPG-6 at m/e=433 to 433.16 of a molecular weight.

Manufacture of Organic EL Device in Example 4

A glass substrate (size: 25 mm×75 mm×1.1 mm thick) having an ITOtransparent electrode (manufactured by GEOMATEC Co., Ltd.) wasultrasonic-cleaned in isopropyl alcohol for five minutes, and thenUV/ozone-cleaned for 30 minutes. A film thickness of ITO transparentelectrode was 70 nm.

After the glass substrate having the transparent electrode line wascleaned, the glass substrate was mounted on a substrate holder of avacuum deposition apparatus. The compound C-1 was evaporated to form a5-nm thick film of the compound C-1 on a surface of the glass substratewhere the transparent electrode line was provided so as to cover thetransparent electrode.

On the film of the compound C-1, the compound HT was evaporated to forma 40-nm thick film of the compound HT. The film of the compound HTserves as the hole transporting layer.

Further, on the film of the compound HT, the compound PG-1 (first hostmaterial), the compound PG-2 (second host material) and the compoundIr(ppy)₃ (phosphorescent dopant material) were co-evaporated to form a35-nm thick emitting layer. In the emitting layer, concentrations of thecompound Ir(ppy)₃, the compound PG-1 and the compound PG-2 wererespectively 10.0 mass %, 45.0 mass % and 45.0 mass %. Thisco-evaporated film serves as the emitting layer.

Following the film formation of the emitting layer, the compound ET2 wasevaporated to form a 30-nm thick film of the compound ET2. The film ofthe compound ET2 serves as the electron transporting layer.

Next, a 1-nm thick film of LiF was formed as an electron-injectingelectrode (cathode) at a film-forming speed of 0.1 Å/min. A metal Al wasevaporated on the LiF film to form an 80-nm thick metal cathode.

Thus, an organic EL device of Example 4 was manufactured.

Manufacture of Organic EL Device in Example 5

An organic EL device in Example 5 was manufactured in the same manner asthe organic EL device in Example 4 except that the film thickness of theITO transparent electrode was changed to 100 nm, the thickness of theco-evaporated film of the emitting layer was changed to 25 nm, thecompound PG-3 was used as the first host material contained in theemitting layer, the compound PG-4 was used as the second host material,Ir(bzq)₃ was used as the phosphorescent dopant material, theconcentrations of the compounds Ir(bzq)₃, PG-3 and PG-4 in the emittinglayer were set at 5.0 mass %, 47.5 mass % and 47.5 mass %, and the filmthickness of the compound ET2 as the electron transporting layer waschanged to 35 nm.

Manufacture of Organic EL Device in Example 6

An organic EL device in Example 6 was manufactured in the same manner asthe organic EL device in Example 4 except that the film thickness of theITO transparent electrode was changed to 130 nm, the thickness of theco-evaporated film of the emitting layer was changed to 40 nm, thecompound PG-5 was used as the first host material contained in theemitting layer, the compound PG-6 was used as the second host material,PQIr(acac)₂ was used as the phosphorescent dopant material, theconcentrations of the compounds PQIr(acac)₂, PG-5 and PG-6 in theemitting layer were set at 3.0 mass %, 87.0 mass % and 10.0 mass %, andthe film thickness of the compound ET2 as the electron transportinglayer was changed to 40 nm.

Evaluation of Organic EL Devices in Examples 4 to 6

The prepared organic EL devices were evaluated in terms of a drivevoltage, an external quantum efficiency EQE and a lifetime LT80. Theresults are shown in Table 3.

Drive Voltage

Electrical current was applied between ITO and Al such that a currentdensity was 10 mA/cm², where voltage (unit: V) was measured.

External Quantum Efficiency EQE

Voltage was applied on each of the organic EL devices at the roomtemperature such that a current density was 10 mA/cm², where EL emissionspectrum was measured by a spectroradiometer (CS-1000 manufactured byKonica Minolta Holdings, Inc.). The external quantum efficiency EQE(unit: %) was calculated based on the obtained spectral-radiancespectra, assuming that the spectra was provided under a Lambertianradiation.

Lifetime LT80

A 80%-lifetime at a current density of 50 mA/cm² was obtained. The80%-lifetime means an elapsed time until a luminance intensity isreduced to 80% of an initial luminance intensity when each of theorganic devices is driven at a constant current. The 80%-lifetime isoccasionally referred to as LT80.

TABLE 3 Host material of Emitting Votage (V) EQE (%) LT80 (hrs) layer10(mA/cm²) 10(mA/cm²) 50(mA/cm²) Example 4 PG-1:PG-2 3.5 18.3 380Example 5 PG-3:PG-4 3.8 16.5 820 Example 6 PG-5:PG-6 4.2 17.2 1,320

Lifetimes of the organic el devices in Examples 4 to 6 were alsoprolonged.

What is claimed is:
 1. An organic electroluminescence device comprising:an anode; a cathode opposed to the anode; and an emitting layer providedbetween the anode and the cathode, wherein the emitting layer comprisesa first host material, a second host material and a luminescentmaterial, the first host material comprises a partial structurerepresented by at least one of the following formulae (1) and (2) isrepresented by formula (4),

wherein: M¹ represents a group represented by one of formulae (1) and(2), L¹ represents a single bond, a substituted or unsubstitutedpolyvalent aromatic hydrocarbon group having 6 to 30 ring carbon atoms,a substituted or unsubstituted polyvalent aromatic heterocyclic grouphaving 5 to 30 ring atoms, a cycloalkylene group having 5 to 30 ringcarbon atoms, or a group provided by linking the polyvalent aromatichydrocarbon group, the polyvalent aromatic heterocyclic group and thecycloalkylene group, k is 1 or 2, X¹¹ to X¹⁸ each independentlyrepresent a nitrogen atom or CR^(b), R^(b) each independently representsa hydrogen atom, a halogen atom, a cyano group, a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted alkenyl group having 2 to30 carbon atoms, a substituted or unsubstituted alkynyl group having 2to 30 carbon atoms, a substituted or unsubstituted alkylsilyl grouphaving 3 to 30 carbon atoms, a substituted or unsubstituted arylsilylgroup having 6 to 30 ring carbon atoms, a substituted or unsubstitutedalkoxy group having 1 to 30 carbon atoms, a substituted or unsubstitutedaralkyl group having 6 to 30 ring carbon atoms, or a substituted orunsubstituted aryloxy group having 6 to 30 ring carbon atoms, and a partof one of adjacent two R^(b) in X¹¹ to X¹⁸ is optionally bonded to apart of the other R^(b) to form a cyclic structure, and the second hostmaterial comprises a partial structure represented by the followingformula (3) is represented by formula (3-1) and does not comprise apartial structure represented by the formula (1) or the formula (2),Ar³—Ar¹—(CN)_(r)   (3-1)-Az-(W_(CN))_(p)   (1)-Az-(CN)_(q)   (2)—Ar¹—(CN)_(r)   (3) where: in the formula (1), Az represents asubstituted or unsubstituted aromatic heterocyclic group comprising anitrogen-containing six-membered ring, W_(CN) is an aromatic hydrocarbongroup substituted by at least one cyano group (CN) or an aromaticheterocyclic group substituted by at least one cyano group (CN), p is aninteger of 1 or more, and W_(CN) optionally comprises a substituentother than the cyano group and, when a plurality of W_(CN) are present,the plurality of W_(CN) are mutually the same or different; In theformula (2), Az represents the same as Az of the formula (1), and q isan integer of 1 or more; and Ar³ in the formula (3-1) represents asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, or a substituted or unsubstituted aromaticheterocyclic group having 5 to 30 ring atoms; and in the formula (3)(3-1), Ar¹ is a substituted or unsubstituted aromatic hydrocarbon groupor a substituted or unsubstituted aromatic heterocyclic group, but isnot an aromatic heterocyclic group comprising a nitrogen-containingsix-membered ring, and r is an integer of 1 or more.
 2. The organicelectroluminescence device according to claim 1, wherein the first hostmaterial is represented by at least one of the formulae (1-1) and (2-1),and the second host material is represented by the following formula(3-1),Ar²-Az-(W_(CN))_(p)   (1-1)Ar²-Az-(CN)_(q)   (2-1)Ar³—Ar¹—(CN)_(r)   (3-1) where: Ar² and Ar³ each independently representa substituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, or a substituted or unsubstituted aromaticheterocyclic group having 5 to 30 ring atoms, Az, W_(CN) and p in theformula (1-1) are the same as Az, W_(CN) and p in the formula (1), Azand q in the formula (2-1) are the same as Az and q in the formula (2),and Ar¹ and r in the formula (3-1) are the same as Ar¹ and r in theformula (3).
 3. The organic electroluminescence device according toclaim 1, wherein the first host material is represented by the followingformula (4),

where: M¹ represents a group represented by one of the formulae (1) and(2), L¹ represents a single bond, a substituted or unsubstitutedpolyvalent aromatic hydrocarbon group having 6 to 30 ring carbon atoms,a substituted or unsubstituted polyvalent aromatic heterocyclic grouphaving 5 to 30 ring atoms, a cycloalkylene group having 5 to 30 ringcarbon atoms, or a group provided by linking the polyvalent aromatichydrocarbon group, the polyvalent aromatic heterocyclic group and thecycloalkylene group, k is 1 or 2, X¹¹ to X¹⁸ each independentlyrepresent a nitrogen atom or CR^(b), R^(b) each independently representsa hydrogen atom, a halogen atom, a cyano group, a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted alkenyl group having 2 to30 carbon atoms, a substituted or unsubstituted alkynyl group having 2to 30 carbon atoms, a substituted or unsubstituted alkylsilyl grouphaving 3 to 30 carbon atoms, a substituted or unsubstituted arylsilylgroup having 6 to 30 ring carbon atoms, a substituted or unsubstitutedalkoxy group having 1 to 30 carbon atoms, a substituted or unsubstitutedaralkyl group having 6 to 30 ring carbon atoms, and a substituted orunsubstituted aryloxy group having 6 to 30 ring carbon atoms, and a partof one of adjacent two R^(b) in X¹¹ to X¹⁸ is optionally bonded to apart of the other R^(b) to form a cyclic structure.
 4. The organicelectroluminescence device according to claim 1, wherein the second hostmaterial is represented by the following formula (5),

where: A¹ represents a group represented by the formula (3),—Ar¹—(CN)_(r)   (3) Ar¹ and r in the formula (3) are the same as Ar¹ andr in the formula (3-1), X¹ to X⁸ each independently represent N(nitrogen atom) or CR^(a), R^(a) each independently represents ahydrogen atom, a substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms, a substituted or unsubstitutedaromatic heterocyclic group having 5 to 30 ring atoms, a substituted orunsubstituted alkyl group having 1 to 30 carbon atoms, a substituted orunsubstituted silyl group, a halogen atom, or a cyano group, when aplurality of R^(a) are present, the plurality of R^(a) are the same ordifferent, and when at least adjacent two of X¹ to X⁴ and X⁵ to X⁸ areCR^(a), a part of R^(a) in the adjacent CR^(a) is optionally bonded to apart of the other R^(a) to form a cyclic structure.
 5. The organicelectroluminescence device according to claim 3 1, wherein the firsthost material is represented by at least one of the following formulae(4-3) and (4-4),

where: L¹ and X¹¹ to X¹⁸ are the same as L¹ and X¹¹ to X¹⁸ in theformula (4), Az, W_(CN) and p in the formula (4-3) are the same as Az,W_(CN) and p in the formula (1), and Az and q in the formula (4-4) arethe same as Az and q in the formula (1).
 6. The organicelectroluminescence device according to claim 4, wherein the first hostmaterial is represented by at least one of the following formulae (4-3)and (4-4),

where: L¹ represents a single bond, a substituted or unsubstitutedpolyvalent aromatic hydrocarbon group having 6 to 30 ring carbon atoms,a substituted or unsubstituted polyvalent aromatic heterocyclic grouphaving 5 to 30 ring atoms, a cycloalkylene group having 5 to 30 ringcarbon atoms, or a group provided by linking the polyvalent aromatichydrocarbon group, the polyvalent aromatic heterocyclic group and thecycloalkylene group, X¹¹ to X¹⁸ each independently represent a nitrogenatom or CR^(b), R^(b) each independently represents a hydrogen atom, ahalogen atom, a cyano group, a substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms, a substituted orunsubstituted heterocyclic group having 5 to 30 ring atoms, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted alkenyl group having 2 to 30 carbon atoms,a substituted or unsubstituted alkynyl group having 2 to 30 carbonatoms, a substituted or unsubstituted alkylsilyl group having 3 to 30carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to30 ring carbon atoms, a substituted or unsubstituted alkoxy group having1 to 30 carbon atoms, a substituted or unsubstituted aralkyl grouphaving 6 to 30 ring carbon atoms, and or a substituted or unsubstitutedaryloxy group having 6 to 30 ring carbon atoms, and a part of one ofadjacent two R^(b) in X¹¹ to X¹⁸ is optionally bonded to a part of theother R^(b) to form a cyclic structure, Az, W_(CN) and p in the formula(4-3) are the same as Az, W_(CN) and p in the formula (1), and Az and qin the formula (4-4) are the same as Az and q in the formula (1).
 7. Theorganic electroluminescence device according to claim 1, wherein thesecond host material is represented by the following formula (5-1),

where: A¹ represents the group having the partial structure representedby the formula (3),—Ar¹—(CN)_(r)   (3) Ar¹ and r in the formula (3) are the same as Ar¹ andr in the formula (3-1), A² each independently represents the grouphaving the partial structure represented by the formula (3), asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, or a substituted or unsubstituted aromaticheterocyclic group having 5 to 30 ring atoms, A³ represents asubstituted or unsubstituted divalent aromatic hydrocarbon group having6 to 30 ring carbon atoms, a substituted or unsubstituted divalentaromatic heterocyclic group having 5 to 30 ring atoms, a substituted orunsubstituted cycloalkylene group having 5 to 30 ring carbon atoms, or agroup provided by linking the divalent aromatic hydrocarbon group, thedivalent aromatic heterocyclic group and the cycloalkylene group, m isan integer of 0 to 3, X¹ to X⁴ and Y⁵ to Y⁸ each independently representN (nitrogen atom) or CR^(a), X⁵ to X⁸ and Y¹ to Y⁴ each independentlyrepresent N (nitrogen atom), CR^(a) or a carbon atom to be bonded to A³,R^(a) in X¹ to X⁸ and Y¹ to Y⁸ each independently represents a hydrogenatom, a substituted or unsubstituted aromatic hydrocarbon group having 6to 30 ring carbon atoms, a substituted or unsubstituted aromaticheterocyclic group having 5 to 30 ring atoms, a substituted orunsubstituted alkyl group having 1 to 30 carbon atoms, a substituted orunsubstituted silyl group, a halogen atom, or a cyano group, when aplurality of R^(a) are present, the plurality of R^(a) are the same ordifferent, and when at least adjacent two of X¹ to X⁸ and Y¹ to Y⁸ areCR^(a), a part of R^(a) in the adjacent CR^(a) is optionally bonded to apart of the other R^(a) to form a cyclic structure.
 8. The organicelectroluminescence device according to claim 3, wherein the second hostmaterial is represented by the following formula (5-1),

where: A¹ represents the group having the partial structure representedby the formula (3), A² each independently represents the group havingthe partial structure represented by the formula (3), a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, or a substituted or unsubstituted aromatic heterocyclic grouphaving 5 to 30 ring atoms, A³ represents a substituted or unsubstituteddivalent aromatic hydrocarbon group having 6 to 30 ring carbon atoms, asubstituted or unsubstituted divalent aromatic heterocyclic group having5 to 30 ring atoms, a substituted or unsubstituted cycloalkylene grouphaving 5 to 30 ring carbon atoms, or a group provided by linking thedivalent aromatic hydrocarbon group, the divalent aromatic heterocyclicgroup and the cycloalkylene group, m is an integer of 0 to 3, X¹ to X⁴and Y⁵ to Y⁸ each independently represent N (nitrogen atom) or CR^(a),X⁵ to X⁸ and Y¹ to Y⁴ each independently represent N (nitrogen atom),CR^(a) or a carbon atom to be bonded to A³, R^(a) in X¹ to X⁸ and Y¹ toY⁸ each independently represents a hydrogen atom, a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms, a substituted or unsubstituted aromatic heterocyclic group having5 to 30 ring atoms, a substituted or unsubstituted alkyl group having 1to 30 carbon atoms, a substituted or unsubstituted silyl group, ahalogen atom, or a cyano group, when a plurality of R^(a) are present,the plurality of R^(a) are the same or different, and when at leastadjacent two of X¹ to X⁸ and Y¹ to Y⁸ are CR^(a), a part of R^(a) in theadjacent CR^(a) is optionally bonded to a part of the other R^(a) toform a cyclic structure.
 9. The organic electroluminescence deviceaccording to claim 5, wherein the second host material is represented bythe following formula (5-1),

where: A¹ represents the group having the partial structure representedby the formula (3),—Ar¹—(CN)_(r)   (3) Ar¹ and r in the formula (3) are the same as Ar¹ andr in the formula (3-1), A² each independently represents the grouphaving the partial structure represented by the formula (3), asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, or a substituted or unsubstituted aromaticheterocyclic group having 5 to 30 ring atoms, A³ represents asubstituted or unsubstituted divalent aromatic hydrocarbon group having6 to 30 ring carbon atoms, a substituted or unsubstituted divalentaromatic heterocyclic group having 5 to 30 ring atoms, a substituted orunsubstituted cycloalkylene group having 5 to 30 ring carbon atoms, or agroup provided by linking the divalent aromatic hydrocarbon group, thedivalent aromatic heterocyclic group and the cycloalkylene group, m isan integer of 0 to 3, X¹ to X⁴ and Y⁵ to Y⁸ each independently representN (nitrogen atom) or CR^(a), X⁵ to X⁸ and Y¹ to Y⁴ each independentlyrepresent N (nitrogen atom), CR^(a) or a carbon atom to be bonded to A³,R^(a) in X¹ to X⁸ and Y¹ to Y⁸ each independently represents a hydrogenatom, a substituted or unsubstituted aromatic hydrocarbon group having 6to 30 ring carbon atoms, a substituted or unsubstituted aromaticheterocyclic group having 5 to 30 ring atoms, a substituted orunsubstituted alkyl group having 1 to 30 carbon atoms, a substituted orunsubstituted silyl group, a halogen atom, or a cyano group, when aplurality of R^(a) are present, the plurality of R^(a) are the same ordifferent, and when at least adjacent two of X¹ to X⁸ and Y¹ to Y⁸ areCR^(a), a part of R^(a) in the adjacent CR^(a) is optionally bonded to apart of the other R^(a) to form a cyclic structure.
 10. The organicelectroluminescence device according to claim 3 1, wherein the firsthost material is represented by the following formula (4-5),

where: L¹ represents the same as L¹ in the formula (4), X¹¹ to X¹⁴ andX⁴⁵ to X⁴⁸ each independently represent a nitrogen atom or CR^(b), X¹⁵to X¹⁸ and X⁴¹ to X⁴⁴ each independently represent a nitrogen atom,CR^(b) or a carbon atom to be bonded to L², R^(b) of CR^(b) in X¹¹ toX¹⁸ and X⁴¹ to X⁴⁸ is the same as R^(b) of CR^(b) in X¹¹ to X¹⁸ in theformula (4), L² and L³ each independently represent a single bond, asubstituted or unsubstituted divalent aromatic hydrocarbon group having6 to 30 ring carbon atoms, a substituted or unsubstituted divalentaromatic heterocyclic group having 5 to 30 ring atoms, a cycloalkylenegroup having 5 to 30 ring carbon atoms, or a group provided by linkingthe divalent aromatic hydrocarbon group, the divalent aromaticheterocyclic group and the cycloalkylene group, a part of one of atleast adjacent two R^(b) in X¹¹ to X¹⁸ and X⁴¹ to X⁴⁸ is optionallybonded to a part of the other R^(b) to form a cyclic structure, M¹represents a group represented by one of the formulae (1) and (2), M²represents a substituted or unsubstituted aromatic hydrocarbon grouphaving 6 to 30 ring carbon atoms, a substituted or unsubstitutedaromatic heterocyclic group having 5 to 30 ring atoms, or a grouprepresented by one of the formulae (1) and (2), and M¹ and M² are thesame or different.
 11. The organic electroluminescence device accordingto claim 7, wherein the first host material is represented by thefollowing formula (4-5),

where: L¹ represents a single bond, a substituted or unsubstitutedpolyvalent aromatic hydrocarbon group having 6 to 30 ring carbon atoms,a substituted or unsubstituted polyvalent aromatic heterocyclic grouphaving 5 to 30 ring atoms, a cycloalkylene group having 5 to 30 ringcarbon atoms, or a group provided by linking the polyvalent aromatichydrocarbon group, the polyvalent aromatic heterocyclic group and thecycloalkylene group, X¹¹ to X¹⁴ and X⁴⁵ to X⁴⁸ each independentlyrepresent a nitrogen atom or CR^(b), X¹⁵ to X¹⁸ and X⁴¹ to X⁴⁴ eachindependently represent a nitrogen atom, CR^(b) or a carbon atom to bebonded to L², R^(b) of CR^(b) in X¹¹ to X¹⁸ and X⁴¹ to X⁴⁸ eachindependently represents a hydrogen atom, a halogen atom, a cyano group,a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, a substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms, a substituted or unsubstituted alkenylgroup having 2 to 30 carbon atoms, a substituted or unsubstitutedalkynyl group having 2 to 30 carbon atoms, a substituted orunsubstituted alkylsilyl group having 3 to 30 carbon atoms, asubstituted or unsubstituted arylsilyl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, and or a substituted or unsubstituted aryloxy group having6 to 30 ring carbon atoms, L² and L³ each independently represent asingle bond, a substituted or unsubstituted divalent aromatichydrocarbon group having 6 to 30 ring carbon atoms, a substituted orunsubstituted divalent aromatic heterocyclic group having 5 to 30 ringatoms, a cycloalkylene group having 5 to 30 ring carbon atoms, or agroup provided by linking the divalent aromatic hydrocarbon group, thedivalent aromatic heterocyclic group and the cycloalkylene group, a partof one of at least adjacent two R^(b) in X¹¹ to X¹⁸ and X⁴¹ to X⁴⁸ isoptionally bonded to a part of the other R^(b) to form a cyclicstructure, M¹ represents a group represented by one of the formulae (1)and (2), M² represents a substituted or unsubstituted aromatichydrocarbon group having 6 to 30 ring carbon atoms, a substituted orunsubstituted aromatic heterocyclic group having 5 to 30 ring atoms, ora group represented by one of the formulae (1) and (2), and M¹ and M²are the same or different.
 12. The organic electroluminescence deviceaccording to claim 1, wherein Az is a divalent to pentavalent group of aring represented by the following formula (4-6),

where: Y¹¹ to Y¹⁵ each independently represent a nitrogen atom (N) orCR^(c), R^(c) of CR^(c) each independently represents a hydrogen atom, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted aromatic heterocyclicgroup having 5 to 30 ring atoms, a substituted or unsubstituted alkylgroup having 1 to 30 carbon atoms, a substituted or unsubstituted silylgroup, or a halogen atom, when adjacent two of Y¹¹ to Y¹⁵ are CR^(c), apart of R^(c) of the adjacent CR^(c) is optionally bonded to a part ofthe other R^(c) to form a cyclic structure, and when a plurality ofR^(c) are present, the plurality of R^(c) are mutually the same ordifferent.
 13. The organic electroluminescence device according to claim3, wherein Az is a divalent to pentavalent group of a ring representedby the following formula (4-6),

where: Y¹¹ to Y¹⁵ each independently represent a nitrogen atom (N) orCR^(c), R^(c) of CR^(c) each independently represents a hydrogen atom, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted aromatic heterocyclicgroup having 5 to 30 ring atoms, a substituted or unsubstituted alkylgroup having 1 to 30 carbon atoms, a substituted or unsubstituted silylgroup, or a halogen atom, when adjacent two of Y¹¹ to Y¹⁵ are CR^(c), apart of R^(c) of the adjacent CR^(c) is optionally bonded to a part ofthe other R^(c) to form a cyclic structure, and when a plurality ofR^(c) are present, the plurality of R^(c) are mutually the same ordifferent.
 14. The organic electroluminescence device according to claim5, wherein Az is a divalent to pentavalent group of a ring representedby the following formula (4-6),

where: Y¹¹ to Y¹⁵ each independently represent a nitrogen atom (N) orCR^(c), R^(c) of CR^(c) each independently represents a hydrogen atom, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted aromatic heterocyclicgroup having 5 to 30 ring atoms, a substituted or unsubstituted alkylgroup having 1 to 30 carbon atoms, a substituted or unsubstituted silylgroup, or a halogen atom, when adjacent two of Y¹¹ to Y¹⁵ are CR^(c), apart of R^(c) of the adjacent CR^(c) is optionally bonded to a part ofthe other R^(c) to form a cyclic structure, and when a plurality ofR^(c) are present, the plurality of R^(c) are mutually the same ordifferent.
 15. The organic electroluminescence device according to claim10, wherein Az is a divalent to pentavalent group of a ring representedby the following formula (4-6),

where: Y¹¹ to Y¹⁵ each independently represent a nitrogen atom (N) orCR^(c), R^(c) of CR^(c) each independently represents a hydrogen atom, asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, a substituted or unsubstituted aromatic heterocyclicgroup having 5 to 30 ring atoms, a substituted or unsubstituted alkylgroup having 1 to 30 carbon atoms, a substituted or unsubstituted silylgroup, or a halogen atom, when adjacent two of Y¹¹ to Y¹⁵ are CR^(c), apart of R^(c) of the adjacent CR^(c) is optionally bonded to a part ofthe other R^(c) to form a cyclic structure, and when a plurality ofR^(c) are present, the plurality of R^(c) are mutually the same ordifferent.
 16. The organic electroluminescence device according to claim10, wherein the first host material represented by the formula (4-5) isrepresented by one of the following formulae (4-5-1), (4-5-2) and(4-5-3),

where: M¹, M², L¹, L², L³, X¹¹ to X¹⁸, and X⁴¹ to X⁴⁸ represent the sameas M¹, M², L¹, L², L³, X¹¹ to X¹⁸, and X⁴¹ to X⁴⁸ in the formula (4-5).17. The organic electroluminescence device according to claim 7, whereinthe second host material represented by the formula (5-1) is preferablyrepresented by one of the following formulae (5-1-1), (5-1-2) and(5-1-3),

where: in the formula (5-1-1), A¹, A², A³, X¹ to X⁵, X⁷, X⁸, Y¹, Y², Y⁴to Y⁸ and m represent the same as A¹, A², A³, X¹ to X⁵, X⁷, X⁸, Y¹, Y²,Y⁴ to Y⁸ and m in the formula (5-1), and X⁶ and Y³ are carbon atoms, inthe formula (5-1-2), A¹, A², A³, X¹ to X⁵, X⁷, X⁸, Y¹, Y³ to Y⁸ and mrepresent the same as A¹, A², A³, X¹ to X⁵, X⁷, X⁸, Y¹, Y³ to Y⁸ and min the formula (5-1), and X⁶ and Y² are carbon atoms, and in the formula(5-1-3), A¹, A², A³, X¹ to X⁶, X⁸, Y¹, Y², Y⁴ to Y⁸ and m represent thesame as A¹, A², A³, X¹ to X⁶, X⁸, Y¹, Y², Y⁴ to Y⁸ and m in the formula(5-1), and X⁷ and Y³ are carbon atoms.
 18. The organicelectroluminescence device according to claim 1, wherein at least one ofthe partial structures represented by the formula (3) partial structure—Ar¹—(CN)_(r) within the formula (3-1) of the second host material is acyano-substituted phenyl group, a cyano-substituted naphthyl group, acyano-substituted phenanthryl group, a cyano-substituted dibenzofuranylgroup, a cyano-substituted biphenylyl group, a cyano-substitutedterphenylyl group, or a cyano-substituted triphenylenyl group.
 19. Theorganic electroluminescence device according to claim 1, wherein theluminescent material comprises a phosphorescent material that is anortho-metalated complex of a metal atom selected from iridium (Ir),osmium (Os) and platinum (Pt).
 20. The organic electroluminescencedevice according to claim 19, wherein a wavelength of an emission peakof the phosphorescent material is 490 nm to 700 nm.
 21. A compoundrepresented by formula (3-2):A-L¹⁰-Ar¹

CN)_(r)   (3-2) wherein L¹⁰ represents a divalent group derived from agroup selected from the group consisting of a phenyl group, naphthylgroup, phenanthryl group, biphenyl group, terphenyl group, quaterphenylgroup, fluoranthenyl group, triphenylenyl group, phenanthrenyl group,fluorenyl group, spirofluorenyl group, 9,9-diphenylfluorenyl group,9,9′-spirobi[9H-fluorene]-2-yl group, 9,9-dimethylfluorenyl group,benzo[c]phenanthrenyl group, benzo[a]triphenylenyl group,naphtho[1,2-c]phenanthrenyl group, naphtho[1,2-a]triphenylenyl group,dibenzo[a,c]triphenylenyl group, benzo[b]fluoranthenyl group, aquinoline ring, isoquinoline ring, quinoxaline ring, phenanthridinering, phenanthroline ring, pyridine ring, pyrazine ring, pyrimidinering, pyridazine ring, triazine ring, acridine ring, piperidine ring,morpholine ring, piperazine ring, a pyrrole ring, isoindole ring,benzofuran ring, isobenzofuran ring, dibenzothiophen ring, indole ring,pyrrolidine ring, dioxane ring, carbazole ring, furan ring, thiophenring, oxazole ring, oxadiazole ring, benzoxazole ring, thiazole ring,thiadiazole ring, benzothiazole ring, triazole ring, imidazole ring,benzimidazole ring, pyrane ring, dibenzofuran ring, andbenzo[c]dibenzofuran ring; Ar¹ represents a group selected from thegroup consisting of a phenyl group, naphthyl group, phenanthryl group,biphenyl group, terphenyl group, quaterphenyl group, fluoranthenylgroup, triphenylenyl group, phenanthrenyl group, fluorenyl group,spirofluorenyl group, 9,9-diphenylfluorenyl group,9,9′-spirobi[9H-fluorene]-2-yl group, 9,9-dimethylfluorenyl group,benzo[c]phenanthrenyl group, benzo[a]triphenylenyl group,naphtho[1,2-c]phenanthrenyl group, naphtho[1,2-a]triphenylenyl group,dibenzo[a,c]triphenylenyl group, benzo[b]fluoranthenyl group, aquinoline ring, isoquinoline ring, quinoxaline ring, phenanthridinering, phenanthroline ring, a pyrrole ring, isoindole ring, benzofuranring, isobenzofuran ring, dibenzothiophen ring, indole ring, pyrrolidinering, dioxane ring, carbazole ring, furan ring, thiophen ring, oxazolering, oxadiazole ring, benzoxazole ring, thiazole ring, thiadiazolering, benzothiazole ring, triazole ring, imidazole ring, benzimidazolering, pyrane ring, dibenzofuran ring, and benzo[c]dibenzofuran ring; ris an integer of 1 or more; A is a group represented by formula (10):

R_(1a) to R_(8a) each independently represent a hydrogen atom or asubstituent; at least one pair of adjacent substituents of R_(1a) toR_(8a) are bonded to each other to form a cyclic structure of formula(11):

R_(10a) to R_(13a) each independently represent a hydrogen atom or asubstituent; X_(1a) and Y_(1a) each independently represent an oxygenatom, a sulfur atom, —NR₂₁—, or —CR₂₂R₂₃—; R₂₁, R₂₂, and R₂₃ eachindependently represent a hydrogen atom or a substituent; and a groupselected from the group consisting of R_(1a) to R_(8a), R_(10a) toR_(13a), and R₂₁ to R₂₃ is bonded to L¹⁰.
 22. The compound of claim 21,wherein A is represented by any of formulae (12) to (17):

R₇₄ to R₁₃₉ each independently represent a hydrogen atom or asubstituent; Y₂₁, Y₃₁, Y₄₁, Y₅₁, Y₆₁, and Y₇₁ each independentlyrepresent an oxygen atom, a sulfur atom, —NR₃₁—, or —CR₃₂R₃₃—; R₃₁, R₃₂,and R₃₃ each independently represent a hydrogen atom or a substituent;if A is represented by formula (12), then a group selected from thegroup consisting of R₇₄ to R₈₄ and R₃₁ to R₃₃ is bonded to L¹⁰; if A isrepresented by formula (13), then a group selected from the groupconsisting of R₈₅ to R₉₅ and R₃₁ to R₃₃ is bonded to L¹⁰; if A isrepresented by formula (14), then a group selected from the groupconsisting of R₉₆ to R₁₀₆ and R₃₁ to R₃₃ is bonded to L¹⁰; if A isrepresented by formula (15), then a group selected from the groupconsisting of R₁₀₇ to R₁₁₇ and R₃₁ to R₃₃ is bonded to L¹⁰; if A isrepresented by formula (16), then a group selected from the groupconsisting of R₁₁₈ to R₁₂₈ and R₃₁ to R₃₃ is bonded to L¹⁰; and if A isrepresented by formula (17), then a group selected from the groupconsisting of R₁₂₉ to R₁₃₉ and R₃₁ to R₃₃ is bonded to L¹⁰.
 23. Thecompound of claim 21, wherein Ar¹ represents a group selected from thegroup consisting of a phenyl group, naphthyl group, phenanthryl group,biphenyl group, terphenyl group, quaterphenyl group, fluoranthenylgroup, triphenylenyl group, phenanthrenyl group, fluorenyl group,spirofluorenyl group, 9,9-diphenylfluorenyl group,9,9′-spirobi[9H-fluorene]-2-yl group, 9,9-dimethylfluorenyl group,benzo[c]phenanthrenyl group, benzo[a]triphenylenyl group,naphtho[1,2-c]phenanthrenyl group, naphtho[1,2-a]triphenylenyl group,dibenzo[a,c]triphenylenyl group, and benzo[b]fluoranthenyl group. 24.The compound of claim 21, wherein Ar¹ represents a group selected fromthe group consisting of a quinoline ring, isoquinoline ring, quinoxalinering, phenanthridine ring, phenanthroline ring, a pyrrole ring,isoindole ring, benzofuran ring, isobenzofuran ring, dibenzothiophenring, indole ring, pyrrolidine ring, dioxane ring, carbazole ring, furanring, thiophen ring, oxazole ring, oxadiazole ring, benzoxazole ring,thiazole ring, thiadiazole ring, benzothiazole ring, triazole ring,imidazole ring, benzimidazole ring, pyrane ring, dibenzofuran ring, andbenzo[c]dibenzofuran ring.
 25. The compound of claim 21, wherein L¹⁰represents a divalent group derived from a group selected from the groupconsisting of a phenyl group, naphthyl group, phenanthryl group,biphenyl group, terphenyl group, quaterphenyl group, fluoranthenylgroup, triphenylenyl group, phenanthrenyl group, fluorenyl group,spirofluorenyl group, 9,9-diphenylfluorenyl group,9,9′-spirobi[9H-fluorene]-2-yl group, 9,9-dimethylfluorenyl group,benzo[c]phenanthrenyl group, benzo[a]triphenylenyl group,naphtho[1,2-c]phenanthrenyl group, naphtho[1,2-a]triphenylenyl group,dibenzo[a,c]triphenylenyl group, and benzo[b]fluoranthenyl group. 26.The compound of claim 21, wherein L¹⁰ represents a divalent groupderived from a group selected from the group consisting of a quinolinering, isoquinoline ring, quinoxaline ring, phenanthridine ring,phenanthroline ring, pyridine ring, pyrazine ring, pyrimidine ring,pyridazine ring, triazine ring, acridine ring, piperidine ring,morpholine ring, piperazine ring, a pyrrole ring, isoindole ring,benzofuran ring, isobenzofuran ring, dibenzothiophen ring, indole ring,pyrrolidine ring, dioxane ring, carbazole ring, furan ring, thiophenring, oxazole ring, oxadiazole ring, benzoxazole ring, thiazole ring,thiadiazole ring, benzothiazole ring, triazole ring, imidazole ring,benzimidazole ring, pyrane ring, dibenzofuran ring, andbenzo[c]dibenzofuran ring.
 27. The compound of claim 21, wherein L¹⁰represents a divalent group derived from a group selected from the groupconsisting of a phenyl group, naphthyl group, phenanthryl group,biphenyl group, terphenyl group, quaterphenyl group, fluoranthenylgroup, triphenylenyl group, phenanthrenyl group, fluorenyl group,spirofluorenyl group, benzofuran ring, dibenzothiophen ring, carbazolering, furan ring, thiophen ring, dibenzofuran ring, andbenzo[c]dibenzofuran ring; and Ar¹ represents a group selected from thegroup consisting of a phenyl group, naphthyl group, phenanthryl group,biphenyl group, terphenyl group, quaterphenyl group, fluoranthenylgroup, triphenylenyl group, phenanthrenyl group, fluorenyl group,spirofluorenyl group, benzofuran ring, dibenzothiophen ring, carbazolering, furan ring, thiophen ring, dibenzofuran ring, benzo[c]dibenzofuranring and a group formed from derivatives thereof.
 28. An organicelectroluminescence device, comprising: a cathode, an anode, and atleast one organic thin film layer between the cathode and the anode,wherein the at least one organic thin film layer comprises a lightemitting layer, and wherein the at least one organic thin film layercomprises a layer that comprises the compound of claim 21.